We need a new DVD player but are completely confused about the Blu-Ray versus HD DVD war. We want to purchase something that will last us many years, but I’m afraid to splurge on it when it’s still unclear what the preferred format will be. One option looks to be buying a DVD player that can “upscale” to high definition. How much worse is this in terms of quality?

The good news is that the war appears to be winding down. Because I never saw any significant quality difference between the two high-definition formats, I never recommended one over the other. But most of the major studios have defected to Blu-Ray, so industry experts believe HD DVD is likely to recede as a movie format, though it may find a market as a data format for computers. However, the companies backing HD DVD haven’t given up, so the battle isn’t formally over.

Meanwhile, I have found that, for everyone but videophiles, “upscaling” DVD players are effective at making most regular DVDs look better on high-definition TV sets. And name-brand models can be found for as little as $45, which is less than Blu-Ray players are likely to commonly cost for quite awhile.

In your review of the new MacBook Air laptop, you said it lacked a wired Internet jack but that Apple plans to sell an adapter. Did you test this? When will it be available? And is there any way to use the MacBook Air with a cellphone network for Internet access?

Apple says the $30 wired Internet adapter will ship when the laptop does. I tested an early unit and found it worked fine. As for working on the cellphone data networks, you can use a cellphone modem from one of the network operators that connects via USB instead of a card slot. Unfortunately, I tested one of these, the Novatel USB727 from Verizon, and found that it was too wide to fit in the cramped space around the MacBook Air’s USB adapter. So you will need an extension cable, making for an ungainly attachment.

There are two other options. If you already own a cellphone data modem meant to fit a PC Card or ExpressCard slot, you can buy an adapter that allows these cards to work via a USB port. I tested such an adapter, a $40 model from a company called Siig that allowed me to use my older Novatel V640 ExpressCard modem with the MacBook Air. It worked well but is relatively large and is attached by a cable, so it is also bulky and ungainly.

The final option would be to pair the MacBook Air with a Bluetooth-equipped cellphone that is able to act as a wireless modem. No cables are required for this, but there is some setup. Ironically, one of the phones that lacks this capability is Apple’s own iPhone.

What happened to the Tablet PC version of Windows? Since Vista has come out, I can’t find a Tablet edition.

Microsoft decided to drop the separate tablet edition it produced for Windows XP and build its capabilities into Vista. Unless you have the least expensive version of Vista, called Home Basic, the full Tablet PC capability should be usable on any tablet PC running Vista. But there’s no longer a specific edition labeled that way.

You can find Mossberg’s Mailbox, and my other columns, online free 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 external modems for a MacBook, resizing photos for email, and using the forthcoming iPhone in Europe.

In your laptop buying guide, you mentioned that the MacBook from Apple lacks both an internal cellphone modem and an external slot in which to insert one. Is there a way to hook up a cellphone modem via a USB port?

Yes, several cellphone carriers offer external modems that plug into USB ports. I haven’t tested these, but have no reason to doubt that they work. However, if you are buying a MacBook, make sure any such modem you buy is Mac-compatible. Both Verizon and Sprint carry a Novatel model that plugs into a USB port and is listed as being compatible with the Mac.

When I email pictures to my sister, she has to scroll up, down, and across to see the whole thing. What can I do to my computer or to hers?

You can make the picture smaller before emailing it. Both Windows and Macintosh computers offer you the option of shrinking the size of photos you email. For instance, in the My Pictures folder in Windows XP, if you select a photo and then choose “Email this file” from the menu at the left, you will be asked if you want to make the picture smaller. On the Mac, in the built-in iPhoto program, when you select a photo and click on the Email icon at the bottom, you are offered a choice of sizes for the picture.

Will the forthcoming Apple iPhone be usable in Europe with a SIM card, and will it be based on a Palm platform or a Microsoft one?

Nothing about any future product can be certain until it is released, but Apple officials have said that the iPhone will be usable in Europe if you insert into it a SIM card from a European carrier. However, it won’t have one of its touted features, “visual voicemail,” which depends upon AT&T, the iPhone’s U.S. carrier.

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Because of the volume of e-mail I receive, I can’t routinely answer individual questions by e-mail, or consult on individual problems or purchasing decisions. I read all questions I receive and select three each week to answer in the column.

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