No, it's not an April Fools' joke.

Apple Computer on Wednesday released Boot Camp software that lets Mac users install Windows XP on their systems. But there are some strings attached, and the company has warned that running Microsoft's operating system on a Mac opens the computer up to the same attacks faced by traditional Windows PCs.

Some Mac users have shown interest in running Windows on Apple's "superior hardware," now that we use Intel processors, Philip Schiller, Apple's senior vice president of worldwide product marketing, said in a statement Wednesday. "We think Boot Camp makes the Mac even more appealing to Windows users considering making the switch," he added.

The software, which will be included in Mac OS X 10.5, known as "Leopard," is available now for download on Apple's Web site. Apple will also preview Boot Camp in August at its Worldwide Developers Conference, the company said.

Windows on a Mac -- what's that all about?
Using Apple's new "Boot Camp" software, you can now install Windows XP alongside the Apple Mac OS X operating system.

How does that work?
Boot Camp creates a separate place on the hard drive, called a partition, for the Windows installation. This is done without moving any of the Mac files. Boot Camp also burns a CD with Windows drivers so the Microsoft operating system can work with the Apple hardware.

How does it run?
After installing Windows XP on the Mac, you can use the "Startup Disk" control panel in Windows or Mac OS X to set which operating system the computer should run when it boots up.

Additionally, holding down the "option" key at startup will display a menu that lets you pick an operating system.

Is this the same as a virtual machine?
No, Boot Camp allows you to run Windows XP natively. That means it runs on the Mac just as it would run on a computer from any other PC maker, such as Dell or Gateway.

What do I need?
In short, you need the latest of everything. You can only run Windows on the newest Intel-based Macs with the most recent firmware, or lower-level software, installed. It must also be loaded with Mac OS X 10.4.6, released earlier this week.

Your Mac will need a built-in keyboard or a USB keyboard, as well as a built-in track pad or USB mouse. It requires 10 gigabytes of free space on your main hard-disk drive. You also have to own or buy a CD with a full version of Windows XP Home Edition or Professional with Service Pack 2 -- that's the latest version of Windows.

What versions of Windows can I run on my Mac?
Windows XP with Service Pack 2. It is not possible to install an earlier version of Windows and upgrade it to XP, nor load an earlier version of XP and update it with SP2. You also cannot use Windows XP Media Center Edition.

In addition, it has to be the full version of Windows XP with SP2, not a cheaper upgrade. Amazon.com sells full XP Home Edition for US$194.99, and Professional is listed at US$284.99.

Will the upcoming Windows Vista work on my Mac?
Apple is sending mixed messages about that, and it declined to provide a yes or no answer on Wednesday.

Before Apple went public about Boot Camp, one of its developers said at an Intel conference that Macs probably wouldn't be able to run Vista. The obstacle, he said, was the different ways the two operating systems have of booting up.

But in its online documentation for Boot Camp, Apple hints that Vista will be supported: "Macs use an ultra-modern industry standard technology called EFI (Extensible Firmware Interface) to handle booting. Sadly, Windows XP, and even the upcoming Vista, are stuck in the 1980s with old-fashioned BIOS. But with Boot Camp, the Mac can operate smoothly in both centuries."

Will Apple provide a copy of Windows XP?
No. Apple does not sell Windows, and Boot Camp does not include XP.

Will my Mac hardware work in Windows?
Not all of it. Even after installing the drivers from the CD created by Boot Camp, some devices will not function correctly with Windows. These include the Apple Remote Control, Bluetooth Apple Wireless keyboard and mouse, Apple USB Modem, MacBook Pro's sudden motion sensor, MacBook Pro's ambient light sensor, and the built-in iSight camera.

What about security? Will running Windows on a Mac expose me to cyberattacks that target Windows users?
Yes! Windows running on a Mac is like Windows running on a PC. That means the system will be subject to the same attacks that are a scourge to the PC world. Be sure to keep your Windows installation updated with the latest Microsoft security fixes. Also, run security software such as antivirus, a firewall and anti-spyware tools.

Will this affect the Mac OS installation that's also on my system?
Probably not. While Apple did not respond when ZDNet Australia sister site CNET News.com asked it this question, Ken Dunham, director of the rapid response team at security company iDefense, did.

"I've been told that by default, Windows will not be able to read the Mac OS X volume on the computer," he said. That would mean that attacks on the Windows part of the machine won't be able to penetrate to the Mac side. "The Windows computer will not by default have access to the Mac OS X volume."

Could any Mac threats affect the Windows side?
That is a remote but possible scenario, Dunham said. Depending on the file system that the Windows installation uses, the Mac OS X software will be able to read and write to the Windows partition.

"Crossover security threats between the Mac OS and Windows OS remain untested and unknown, but may (occur) since it is possible to read and write from the Mac OS to the Windows volume," he said.

What is this file system business?
File systems, such as Windows' current NTFS, make it possible for people and computer programs to find documents, photos and other data.

During installation on the Mac, the Windows XP installer will ask what file system to use to format the Windows partition. It can be NTFS or FAT. If the partition is larger than 32 GB, you can only format it using NTFS. Mac OS X can read and write FAT volumes, but can only read NTFS volumes.

Will Apple help me when I have Windows trouble?
No. Unlike other PC makers, such as Dell, Gateway or Hewlett-Packard, Apple does not sell or support Windows.

Will Apple at least support Boot Camp?
Again, you're mostly on your own. The current version of Boot Camp is a preview, or beta, version. It is licensed for use on a trial basis for a limited time only. Support is available on Apple's Web site, but the company does not provide technical phone support for using the Boot Camp beta, burning the driver's CD or installing Windows XP.

Apple plans to include the Boot Camp technology in the next major release of Mac OS X. That version, called Leopard, is scheduled for release either late this year or early next year.

Can I get help from Microsoft?
Most likely, yes. Microsoft includes limited support when you buy a copy of Windows XP in a store. Also, it offers free support related to security incidents, such as spyware infestations on your system and virus infections. In the U.S., call 1-866-727-2338.

Can I now also run Mac OS X on my standard, Intel-based PC?
Apple has said that it will take steps to prevent this from happening. "We will not allow running Mac OS X on anything other than an Apple Mac," Phil Schiller, company senior vice president, said in a June interview. The company has not gone into specifics, but appears to be using a TPM (trusted protection module) chip as part of its authentication mechanism.

Where do I get Boot Camp?
A preview version is available for free download. However, the Mac maker cautions people to not use it on systems in a commercial operating environment or with important data. You should back up all of your data before installing Boot Camp, it recommends.