How to Triple-Boot Your Mac with Windows and Linux, No Boot Camp Required

Apple has streamlined the process of dual booting Windows on your Mac, but when it comes to Linux, Boot Camp isn't so friendly. Here's how to triple-boot your Mac with OS X, Windows 7, and the shiny new Ubuntu 10.04.

If you're a Mac user, you may have already used Apple's Boot Camp to get Windows on your system for those must-have programs. With a fast new Ubuntu out, however, you might want to give it a try—but installing Linux isn't exactly easy on Macs, since they don't recognize it by default.

Also complicating things? Linux and Windows' boot loaders will attempt to take over one another. Usually, this is a good thing, because Linux's multi-system loader makes the experience more seamless for PC users—but on a Mac, this really just makes things more difficult (no one wants to go through two menus to choose their OS). As such, installing Linux needs to be done with certain settings applied, or you'll be left with a jumbled mess. Here's a step-by-step guide to making your triple booting experience as user-friendly as possible.

Note that I will go through the steps to installing both Windows 7 and Ubuntu 10.04, but if you already have Windows installed, that shouldn't be an issue—just skip the Windows installation step and move on to installing Ubuntu, which is the more complicated (and important) part anyways.

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why i don't need virus software on a Mac?

Ans, i got it while i was just going on with the Discussions on Apple Site at following link:
http://discussions.apple.com/thread.jspa?threadID=2410671&tstart=0