Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability.

Recently, you reviewed some new Apple laptops whose batteries are sealed in and can’t be removed by the user. But I have had situations with some laptops where the only way to restart them when frozen is to remove the battery. How can this problem be handled if the battery is sealed in?

On Mac laptops, you can shut down the computer, even if the software appears frozen, by holding down the power button firmly and continuously for 5-10 seconds. You then wait a few seconds, press the power button again, and the machine should start up. This is different from the more common scenario where a brief press of the power button brings up a dialog box allowing you to choose to shut down or restart the Mac, or to put it into sleep mode.

Apple says there is another method you can use instead of removing a battery. Pressing the Control and Command keys simultaneously with the Power Button restarts the computer.

I live in the U.S. and when I visit Europe I have no cellphone, which makes it difficult to stay in touch during my trips. I am completely ignorant about cellphones and use a pay-as-you-go model that doesn’t work in Europe. What type of phone do you recommend I buy that I can use both in the States and abroad? I do not need a built-in camera, or any other fancy add-ons. I only want to be able to call people.

The two major U.S. phone carriers whose underlying technology is compatible with the system used in Europe are AT&T and T-Mobile. Given your needs and your usage pattern, I’d go into one of their stores and look for the least expensive and simplest model that can operate on all the frequencies used in the U.S. and Europe. These phones are typically referred to as “quad band” or sometimes as “world phones.” I would also try and find a plan that minimizes overseas roaming charges, which can be quite high.

Another option is to look for an “unlocked” phone that can accept different SIM cards, the small chips that connect phones to carriers. That way, you could have one SIM for use in the U.S. and another for whatever country you are visiting.

I have hundreds of folders in “My documents.” In each folder there may be hundreds more individual files. Is there a way to rapidly search for key words in all of those documents in order to locate any files that might contain a particular word?

If you are using Windows XP, you can download and install various desktop search add-on products that can solve your problem. The best known are Windows search, from Microsoft, at http://bit.ly/Dflai, and Google Desktop Search, at desktop.google.com. If you have Windows Vista, it comes with a built-in desktop search function that can accomplish that task, though you can also use the Google product.

You can find Mossberg’s Mailbox, and my other columns, online for free at the All Things Digital web site, http://walt.allthingsd.com.

Is there a way to transfer a Windows Media music file to iTunes?

If the Windows Media file is copy-protected, typically because you bought it from an online store that copy-protects its music, iTunes cannot import or play it. However, if it is unprotected, which is typical for files you created from your own CDs using Windows Media Player, iTunes can import the file and automatically convert it into a format it can use.

I would like to purchase an iPhone, but run it on the Verizon network. I realize that AT&T has an exclusive at this time, but is there a way to do this on the secondary market?

No. The radio inside the iPhone is incompatible with the network technology used by Verizon and Sprint. That cannot be changed by hacking the software, or replacing the SIM card in the phone.

I need to buy a new laptop computer and am wondering if you think Vista is wise at this point or should I still stick with Windows XP if I can find it? I only do emails, browsing the net and some downloading of music and photos. I am retired and don’t know much about computers.

Vista easily handles the tasks you want to do, but it will require heftier hardware to work at acceptable speeds, and, assuming you are used to working with XP, Vista will require you to learn some new things. If you buy XP, you can get away with a more modestly equipped computer, and you will be working with a more familiar interface. So, in your particular situation, I would suggest an XP machine. But I urge you to make sure it gets upgraded to the latest revision, called SP3, which bolsters the security of XP, so it is closer to that of Vista. Depending on your setup, this upgrade may be delivered automatically by Microsoft, but you may have to agree to accept it.

You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

I am considering the purchase of the MacBook Air (AAPL). If this computer freezes up, as my current Dell Inspiron does on occasion, how would I correct for that? I usually remove and then replace the battery on the Dell (DELL). But what would I do if this happens with the Air, since it has no removable battery?

You can force a frozen MacBook Air — or any current Mac laptop — to shut down and restart without removing its battery. You just hold down the power button for a few seconds until the machine shuts off, then wait a few seconds, then turn it on again.

I am a Verizon (VZ) customer and have a Palm (PALM) Treo 700W for personal use. I would like to replace the Treo but, in light of Verizon’s announced “open network” policy, I am wondering if this is the right time.

It’s far too early to know what new phones will be available under the new Verizon program, since that depends on which phone makers decide to make devices to run on the “open” network, and what kinds of devices they might produce. There is the potential for phones that are more creative or interesting than what is available today, but it’s only a potential. Verizon has just laid out the first details of the plan, and no product announcements are likely for quite a while. If your Treo needs replacing soon, and you want to remain a Verizon customer, you will have to choose from the company’s current smart-phone offerings.

Are there any cellphones that allow for two separate phone numbers? Right now I carry two devices, both with the same carrier.

At least in the U.S., each cellphone, or each SIM card that goes in a phone, is normally tied to a single number. To use two numbers on a single phone, you could purchase an unlocked phone running on a GSM network and then purchase two SIM cards, each with a separate number, and swap them in and out. But that would be an inconvenient process, since inserting and removing SIM cards typically requires opening the phone and even removing the battery.

You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability. This week my mailbox contained questions about using an iPhone overseas for data purposes, running Microsoft Office 2000 on Vista and using broadband-provider email in two locations.

You recently wrote that iPhone owners using the device overseas must roam on AT&T at high rates, because the iPhone won’t work with SIM cards from foreign carriers. You noted that AT&T has a monthly plan that cuts these per-call voice rates somewhat. But what are the options for using an iPhone overseas for data purposes, such as email and Internet browsing?

Until Apple initiates iPhone service with foreign carriers, which is expected to be a gradual process that will begin in Europe, iPhone owners traveling abroad will be forced to roam on AT&T and to pay through the nose for data as well as voice calls made over cellular-phone networks. They won’t be able to buy cheaper service from a local foreign carrier and enable it by simply replacing the phone’s AT&T SIM card with the local carrier’s.

In addition, it is important to note that, even if you are willing to swallow these huge voice-and-data rates, you must call AT&T (formerly Cingular) before you leave the U.S. with your iPhone (or any AT&T phone) to modify, or “provision,” your calling plan so it will even work overseas.

Here are the details. Note that these prices and plans apply to many other phones AT&T sells, not just the iPhone.

To recap the voice-calling situation, AT&T charges very high fees, which can be mitigated a bit by adding a special $5.99 monthly add-on feature, called AT&T World Traveler, to their plans. This voice feature allows you to roam in 190 countries and gives you discounts on calls from 80 countries. For instance, in France, Italy, Germany, and Britain, you pay a still-high 99 cents a minute, compared with an even worse $1.29 without the plan. In Hong Kong or Israel, you pay a whopping $1.99 a minute, instead of an even more outrageous $2.29 or $2.49, respectively, a minute.

For email and the Web, the best bet for iPhone owners is to avoid using cellular networks and employ the phone’s Wi-Fi capability, which can cost nothing extra. Try to find a free or reasonably priced Wi-Fi hot spot in which to check email and do Web browsing. You may even be able to make cheap voice calls this way using Internet-based calling services like JaJah (mobile.jajah.com) which, in my domestic tests, worked properly via the iPhone’s Web browser.

However, if you need to check email constantly or frequently, you are unlikely to be able to depend solely on the Wi-Fi method. You can rely on AT&T roaming to do this over foreign cellular services, but, as with the voice call situation, it will cost a fortune.

AT&T offers an add-on plan for $24.99 a month, called the “PDA/Smartphone/iPhone International Data Plan.” This is on top of the $5.99-a-month voice plan, and is also additive to the $20 a month for unlimited data when in the U.S. that is built into your base plan. But it isn’t unlimited. You get only 20 megabytes of overseas data use a month, and pay a stiff $.005 a kilobyte for all data use above that.

Plus, this international-data plan only works in 29 countries. Outside those countries, the cost is an astounding $.0195 a kilobyte, or roughly $20 a megabyte. To put that in perspective, a single email with a medium-resolution picture attached could amount to a megabyte. More information is at www.att.com/wirelessinternational.

One more note: apparently AT&T can and will cancel your roaming service overseas if it notices what it considers an unusually high number of calls being made. One reader with an iPhone reported that, after arranging belatedly in Europe to get the voice-roaming service, he was suddenly cut off when he reached India, with AT&T explaining the cutoff as an attempt to prevent suspected fraud.

According to this reader, AT&T said he had been cut off “because there were ‘too many calls from India and other countries’ and they did not think it was possible anyone could be doing that for real, so to protect me, they cancelled the service.” An AT&T spokesman says the company can’t comment on the details of this particular case without knowing the traveler’s phone number.

You say Office 2003 runs OK on Windows Vista. I have been using Office 2000 and it does everything I need. Will it also run OK on Vista?

Microsoft doesn’t officially support Office 2000 on Vista. It may work, but I haven’t tested it.

Is there a way that I can use my same email address both at my home in New Jersey and at my winter place in Florida, even though I have broadband Internet service in New Jersey but am limited to dial-up Internet access from a different provider in Florida?

Some broadband providers also make available a supplementary dial-up service for their customers, which may be free or cost extra. Check with your broadband service to see if it offers this option.

If not, you could simply use an email account that isn’t necessarily tied to an access provider at all, such as Web-based email services from Yahoo, Google or Microsoft. You could switch to one of these permanently, and use it in both locations, or you can forward your main email address to one of them while you are in Florida. People who send you email wouldn’t have to learn a new address and many Web-based services allow you to set your main address as the “reply-to” address for emails you send.

You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

Write to Walter S. Mossberg at mossberg@wsj.com

This week, I was swamped with questions about Apple’s hot new iPhone, so this is a special all-iPhone edition of Mossberg’s Mailbox.

Can you physically remove the included AT&T SIM card from the iPhone and replace it with another AT&T card or one from another wireless carrier?

Yes, and no. The SIM card, which carries the iPhone’s account information, can be removed by inserting a paper clip into a tiny hole at the top of the phone. However, Apple says that if you replace the included card with one from another carrier, like T-Mobile in the U.S., or Orange in Europe, the phone won’t work. According to Apple, some non-iPhone AT&T cards may work, but some may not.

It’s possible that hackers will figure out a way to override this lock on other carriers’ SIM cards. But, as of now, the iPhone will work only with AT&T. Even overseas, at least until Apple does deals with foreign partners, you won’t be able to use SIM cards from other carriers. The iPhone will work overseas, but you will have to roam with AT&T and pay high charges. For instance, according to an AT&T spokesman, if you make a call in Europe, it would cost $1.29 a minute. It would cost 99 cents a minute if you are on one of AT&T’s $5.99 per month international plans.

Since the iPhone battery is sealed in and can’t be easily replaced by the user, what happens when it dies? Will you have to buy a new iPhone?

No, but you will have to send the phone to Apple, or drop it off at an Apple store, to have the battery replaced. The battery is covered during the phone’s one-year warranty period. After that, replacing the battery costs $79, plus $6.95 for shipping, and takes three business days. Details are at apple.com/support/iphone/service/battery/. Some small companies may eventually offer to do this for less, or in less time, as they have for the iPod.

One twist: because a phone is a necessity, Apple is offering loaner iPhones for $29 while your phone’s battery is being replaced, or for the period of any other repair on the iPhone. You will have to switch the AT&T SIM card from your own phone to the loaner, and then back again. Details are at apple.com/support/iphone/service/faq.

In addition, Apple warns that all the data on your iPhone will be wiped out during a battery replacement, but notes that it can easily be restored by simply syncing again with the iTunes software on your computer once you get it back with a fresh battery. That’s because, whenever you sync your iPhone with iTunes, it backs up the data on the phone. You can also use this method to fill your loaner iPhone with your own data.

Can I use the iPhone via a Bluetooth wireless connection in my car? Can I use Bluetooth to transfer files or other information between the iPhone and a computer?

In my two-week test of the iPhone, I succeeded in connecting it without much trouble to the built-in audio system and microphone on a friend’s BMW. Almost instantly, the over 700 contacts I had on my test iPhone were displayed on the car’s dashboard screen and calls could be made and received through the iPhone.

However, this first iPhone can use Bluetooth to connect only with cars and with wireless phone headsets. It cannot use Bluetooth to transfer any data to or from a computer, to play music through stereo wireless headsets, or for any other purpose. As with many other missing features, Apple has the ability to add these to the iPhone through software updates delivered by synchronizing with your computer.

If the iPhone’s Web browser is so good, why can’t it play video on Web sites I visit?

At launch, the iPhone version of the Safari browser is missing some plug-ins needed for playing common types of Web videos. The most important of these is the plug-in for Adobe’s Flash technology. Apple says it plans to add that plug-in through an early software update, which I am guessing will occur within the next couple of months. However, a separate program included on the iPhone can play a limited selection of videos from YouTube, and the phone can play videos you purchase from Apple’s iTunes store, and certain videos you create yourself.

You have been critical in the past of some smartphones that don’t allow you to delete emails with a single click. Can the iPhone do this?

Yes. If you are reading an email and want to delete it, you just tap on a trash can icon at the bottom of the screen and the message disappears into the trash can with an animation that resembles water being poured through a funnel.

However, in the iPhone email program’s list view, it takes two steps to delete an email. You have to swipe across the message header or preview with your finger, and then tap the red delete button that appears. You can also press an “Edit” button, which allows you to delete emails in the list view, but this still requires two taps per message.

Unlike on a BlackBerry or Treo, the iPhone doesn’t allow you to delete whole groups of email en masse by date, or even to select large groups and then delete them en masse. This would be a good feature for Apple to add down the line.

Can you buy an iPhone and just use it to play music and videos like an iPod, and to surf the Web or get email over Wi-Fi, without signing up for an AT&T service contract?

No. None of the iPhone’s functions, except calling 911, will work unless the phone is covered by a two-year AT&T service contract, and has been “activated” by AT&T. That will cost you $60 a month at a minimum. If you are thinking of buying an iPhone, you should plan on being an AT&T customer, and if AT&T coverage is poor where you live, work and travel frequently, I advise you NOT to buy an iPhone.

You and many others have criticized AT&T’s EDGE data network, which the iPhone uses, as slow. You have noted that AT&T has a much faster data network. Can the iPhone be upgraded to use that faster network?

No, it can’t. This first edition of the iPhone can’t use any cellular network faster than EDGE, which is much, much slower than the fastest cellphone data networks available from AT&T, Verizon or Sprint. It can, however, use very fast Wi-Fi wireless networks, when you are in range of them.

Apple hasn’t said anything about future iPhone models, but I fully expect a future model that can use these faster cellular networks, which are usually called 3G networks. So, if this is very important to you, I’d suggest waiting to see if such an iPhone emerges. But I don’t expect this to happen anytime soon.

In the past few days, AT&T seems to have tweaked its EDGE network, at least in some locations, so it runs faster than it has in the past. In my own speed tests, around Washington, D.C., I have seen repeated speeds of around 150 kilobits per second, roughly 50% better than the 100 kbps I have seen with EDGE in the past. However, I have also recorded speeds as slow as 82 kbps. And, even the new, faster speeds are way below those of the faster American cellular data networks, which can easily reach 500 to 800 kbps on a phone.

How good is the iPhone’s To-Do list or Task function?

Awful — in the sense that it doesn’t exist. The phone does have a calendar, of course, which syncs with the most popular calendar programs on Windows and Macintosh computers. And it has a Notepad, which doesn’t sync with any program on any computer (though you can email notes to yourself and others). But it has no To-Do list function at all.

Write to Walter S. Mossberg at mossberg@wsj.com