In your spring buyer’s guide, you wrote that adequate graphics chips will be more important than ever, but in the past you’ve advised that memory, or RAM, was key to speed and performance. Can you now get the same gains by buying or adding a better graphics chip? Or is RAM just as important as ever?

There are lots of things that can improve the performance of a PC or Mac. But adding memory still gives you more bang for the buck than any other, in my view. What I was saying last week is that the forthcoming Microsoft and Apple operating systems will be relying more on graphics chips to help take some of the load off the main processor and speed up certain tasks. Even so, a better graphics chip isn’t a substitute for more main memory. In fact, most moderately priced computers use so-called integrated graphics chips, which lack dedicated memory and share some of the computer’s main RAM. So having plenty of main memory is directly related to getting the most out of such graphics chips.

Can the iPhone be connected to desktop peripherals? I want to be able to plug my iPhone into a large monitor and printer.

There are already several apps, including one from Hewlett-Packard, that allow you to print photos wirelessly from an iPhone to a printer that’s connected to a Wi-Fi network. But, as far as I know, there is nothing on the market today that can connect an iPhone to an external monitor or keyboard, or to a printer for nonphoto printing. However, Apple has announced that the new 3.0 version of the iPhone operating system, due this summer, will enhance the ability of the iPhone to work with add-on hardware, either via cables or wirelessly. The company showed this off with medical devices, but it’s possible that some third party could make it work with monitors or printers or keyboards.

A recent article in the Journal reported that a person had installed the Mac operating system on a Windows laptop. Is this really possible and is it legal?

Apple doesn’t sell or license its Mac OS X operating system for use on non-Apple hardware. In fact, the company considers it illegal to install OS X on other brands of computers. Nor does it produce OS X drivers for non-Apple hardware features that are built into competitors’ computers. Nevertheless, some computer hobbyists have installed OS X on non-Apple hardware, and posted photos and videos online to prove it.

Even if you are willing to ignore the legal issues, this process, while not brain surgery, takes more skill than the average user possesses. And, in the end, some features of the computer may wind up disabled or require workarounds to function. For instance, on one such machine I saw, the speaker port didn’t work with the Mac OS.

• 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 thinking about buying an iPhone to replace my Palm Treo. However, I have an extensive contact list and calendar within my Palm software. How would I transfer them to the iPhone?

There are a number of cumbersome methods, but a simple approach would be to sync the Treo to Microsoft Outlook, which can then later be synced to the iPhone.

You say Vista’s graphical interface works best with a separate, or “discrete,” graphics card that has its own memory. You add that some “integrated” graphics systems work fine, too, but they claim some of your main memory. So, if I get an extra 1 GB of main memory, will that compensate for not getting a dedicated video card?

Buying extra memory can help overall performance on systems with minimal standard memory and integrated graphics, which do drain memory. So I’m all for that. But the superiority of discrete graphics cards for Vista goes beyond the fact that they have their own memory. In general, they are more capable than integrated graphics at doing the actual graphics processing. So adding more memory to a system with integrated graphics doesn’t give it all the ability of one with a discrete card.

Is there any program or easy way of transferring email addresses when you change your ISP? Everybody I have talked to says it is a mess.

Although I haven’t tested it in some years, a service called TrueSwitch, at trueswitch.com, is in business to do exactly that. It copies over your address book, and even notifies your contacts of your changed email address, if you wish. When I did test it, it worked fine.

• 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.

A friend of mine suggested that I “defragment” my computer every once in a while. He says it will boost performance, but he also said it will move my data around. I tend to be very organized as to where I put documents on my computer. Will defragmenting my computer jumble my files and put them into random places?

No. Defragmenting a hard disk doesn’t change or scramble the organization of files and folders that you have established. Your file organization should look just the same after defragmenting the disk. What defragmenting does is rearrange the location on the disk of the data segments that make up your files. In some cases, a single file like a word-processor document might actually be made up of multiple data segments, invisible to you, that are located in widely separated physical spots on the disk. Defragmenting tries to optimize the location of these segments so that the computer operates more efficiently.

I saw your review of Norton Internet Security 2009, and wonder what is the difference between this product and Norton 360?

Norton 360 has the same features as Norton Internet Security, but adds some additional ones, like online backup and PC “tune-up.” It also costs more. However, the current version of Norton 360 doesn’t include the improvements I wrote about in the NIS product that make it faster and less of a burden on your computer. Those are planned for a future version of Norton 360.

Can I use one of the new 3G iPhones as a wireless modem for my Apple laptop?

No. That function isn’t built into the iPhone and Apple yanked from distribution a third-party program that enabled using the phone as a modem. I suspect the reason is a business one, not a technical one. Cellphone carriers like AT&T typically take the position that connecting a laptop to their networks, whether via a data card or via a cellphone used as a modem, should command a higher monthly data charge than they typically levy for a cellphone alone.

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