Some time ago you wrote in an article about software that erases files and then records over them, as the safest way to clean off a hard disk. Could you identify the software?

A:

If you are using a Windows PC, there are multiple programs, both free and paid, called “file wipers,” that can do this. One I have recommended is Window Washer from Webroot, which, among other things, does what the company calls “bleaching” of files so they can’t be easily recovered. If you’re using a Mac, a similar feature is built into the latest operating system versions. It’s called “Secure Empty Trash” and is found in the Finder, the Mac’s equivalent of Windows Explorer.

Q:

In your recent article about transferring Internet video to your TV, you ignored Apple TV. Why?

A:

Because the article was about methods for wirelessly streaming video from multiple Web sites via a PC to a TV, and that’s not what Apple TV primarily does. It mainly takes audio, video and photos that are already on your computers and plays or displays them on your TV. It only directly streams in real time from YouTube and Internet radio sites, plus content being downloaded from iTunes. Unlike the two products I covered, Apple TV doesn’t allow you to stream movies or TV programs from a variety of Web sites you choose, like Hulu or CBS.com (CBS).

Q:

If I get a magicJack, when I call another magicJack, can we engage the computer’s camera to converse?

A:

No, magicJack is an audio device, not a video one. It isn’t like Skype, which can do both.

You can find Mossberg’s Mailbox, and my other columns, online at walt.allthingsd.com.

Has anyone come up with a method that allows people to take pictures with a regular digital camera and then download them wirelessly to a computer, and/or perhaps to the Internet?

There have been a few digital cameras with built-in Wi-Fi wireless capability, but the best and simplest method I know is a $100 product called Eye-Fi. This tiny gadget looks and works like a regular, garden-variety SD memory card, but it packs a Wi-Fi transmitter inside. It fits into a standard SD memory-card slot and is compatible with a wide range of camera models from Canon (CAJ), Kodak (EK), Nikon (NINOF.PK) and others.

Coupled with clever software, and a clever Web site, the Eye-Fi card automatically zips your pictures wirelessly to your PC or Mac, and/or to your choice of over 20 online photo-sharing services.

For more information, see www.eye.fi. For a list of compatible cameras, see support.eye.fi/compatibility/. For a full review of the product, see: solution.allthingsd.com/20071121/.

You mentioned last week that SugarSync might be a good solution for backups, so if one computer dies your files still exist on another system. But what if the doomed computer doesn’t actually die but its files are corrupted by malicious software? Do those newly corrupted files overwrite the good copies on your SugarSync network?

They could do so, depending on which folders you had chosen to replicate on your other computers. Automatic-synchronization services like SugarSync have a tough time telling whether changes to a file are deliberate, accidental or the result of some sort of corruption. Though the last is rare, it could look to SugarSync like you had changed the file on purpose.

One way to guard against that is for a service to offer “versioning” — the practice of maintaining multiple past copies of a file. That way, if a change isn’t intentional, you can go back to the prior, pristine version. Sharpcast, the company that makes SugarSync, says it is planning to add versioning to the service, but offers no specific date. In the meantime, one way to back up a file without fear of its being overwritten by a corrupted version is to upload it to SugarSync’s special “Web Archive” folder, whose contents are never automatically updated.

Have you ever reviewed and suggested a media player for connecting to a home theater to play all songs, videos and photos that exist on your home computers?

Yes, I have reviewed several over the years. The one I find simplest and best designed is Apple TV, which, despite its name, can work fine in a household with no other Apple (AAPL) hardware. It costs $229 and is a small, thin, unobtrusive box that fetches music, photos and videos from your home network using either a wired or a wireless connection. It can connect to your TV set or home theater via a variety of analog and digital ports, including component-video, HDMI, and optical and analog audio. It supports high-definition video and works with any computer, Windows or Mac, that has Apple’s free iTunes software installed and running.

Apple TV handles many standard photo, music and video formats, but it is limited to music and video files that iTunes can handle. That excludes copy-protected files in Microsoft’s formats, and certain open Microsoft formats, but includes common files like MP3s. Apple TV also allows you to access YouTube and to purchase music and TV shows from Apple, and rent movies from Apple, without the use of a computer.

• You can find Mossberg’s Mailbox, and my other columns, online for 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 finding a simple cellphone, Apple TV’s video formats and networking two Windows PCs.

I am approaching 70, and I wonder if there is a “simple” cellphone available, or something close? I want one that merely makes and receives calls, records messages, and retrieves messages with the push of a button.

Most cellphone carriers and electronics retailers sell very basic phones that mainly do just that. If they have additional functions they are optional. Another choice is a phone called the Jitterbug, which not only focuses on these basic functions, but also has large buttons and other features designed for older users. More information is at jitterbug.com. Our review of the Jitterbug can be found at: ptech.wsj.com/archive/solution-20061101.html

Will the Apple TV play back non-copy-protected video in the AVI format?

No. Apple TV doesn’t support AVI. The principal non-copy-protected video format it supports is MP4. It also supports copy-protected video, but only in the format used by Apple’s iTunes Store. Apple’s free QuickTime program, which comes with the iTunes software for both Windows and Mac computers, has a function that can convert some types of video files into formats that Apple TV can use.

I have a laptop that operates on Windows XP. If I get a new desktop with Windows Vista will I have any problems networking the two of them?

Networking in Windows can be flaky, and it’s impossible to say with certainty that you won’t have any problems. But I can say that, in my own limited tests, mixed networks of Windows XP and Windows Vista computers worked properly.

* * *

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

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 Apple TV with older sets, the pricing of Apple TV and using SmartSync Pro on Vista.

In your review of Apple TV last week you said it wouldn’t work on a standard, non-widescreen TV, but I have seen reports that it does work on these sets. How is that possible?

What we wrote was that it was designed for newer, widescreen sets, especially high-definition sets, and wouldn’t work on older, square-type sets, “unless they can display widescreen-formatted content and accept some newer types of cables.” Some older TVs can do this, but many cannot. The sets must have connections called component or HDMI, which many older sets lack, especially lower-priced ones, even if they can display widescreen content.

I have also heard reports that you can use Apple TV on older sets that cannot handle widescreen content. But my guess is that, on these sets, the menus and user interface are distorted.

I have just bought a new Dell Vista computer. None of my backup software now works. Does SmartSync Pro work with Vista? Do you have any suggestions?

SmartSync Pro, a program I have recommended in the past, regularly crashes on my own Vista desktop, though its maker, SmartSync Software, claims most features do work on Vista. The company says it is working on a new Vista version. In general, this is a major problem with adopting Vista. It is amazing to me that so many hardware and software vendors still haven’t issued Vista-compatible versions or drivers.

One suggestion might be to try the internal backup and restore function in Vista, which Microsoft claims is improved over what was available in Windows XP. I haven’t tested it, but more information is here.

In your Apple TV review, you said the Xbox 360 costs 50% more. But aren’t they priced the same, at $299?

I said the “comparable” Xbox 360 model was 50% more than Apple TV, and in making that calculation, I was being kind to the Xbox. The base, $299.99 “core” model of the Xbox 360 has no hard disk, so, to be comparable to Apple TV, which does, you would need the high-end Xbox 360, which costs $399.99 and includes a hard disk. But even this high-end Xbox 360 doesn’t have Wi-Fi wireless networking, which is built into Apple TV and is needed to stream PC-based content to TVs in the many, many homes that lack wired networks.

To get Wi-Fi on an Xbox 360, you must spend $100 for an optional adapter, which brings the cost to $499.99. But I assumed a user might be able to find a wireless adapter for $50, so I rounded the price down to $449.99, which is slightly greater than a 50% premium over the Apple TV. Even with that premium, the Xbox offers slower wireless speeds, and a hard disk only half as large.

Next month, a new Xbox 360 model is expected to be available that will have a 120-gigabyte hard disk — triple the size of the Apple TV’s disk. It is likely to cost $479.99, but still won’t include wireless networking.

As I noted in the column, the Xbox 360 can do some media tasks the Apple TV can’t do, and, of course, it is also a full-blown game console, unlike the Apple TV. That may make the Xbox’s higher price well worth it for some.

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