Yes, before you fire off a flaming comment, we know this is The Unofficial Apple Weblog, but we thought it might be nice to post a tip for those of you who either want or need to play with the next generation of Microsoft Windows, reportedly due out within the decade (hey, it was originally due in 2003 - by its present 2007 date they'll be almost half a decade late already). This Apple Discussions forum thread details a slightly more appealing trick for getting Vista, now in a public beta (but overloaded with download requests as of this writing), to install and run with Boot Camp. Basically, you need to have Boot Camp already set up and installed with Windows XP. Then, burn a DVD of the Vista beta you just downloaded. And before you ask: no, unfortunately, Vista won't run on Parallels Desktop - yet. Parallels has publicly mentioned making this work with a future version, but there is no ETA for when this support will land.
Now - and this is the 'at your own risk' part - you need to use some kind of partition manager (the forum poster used one from within XP, but I've heard you can use one that starts up from within the Vista installer when booting from the DVD) to delete an ambiguous partition that Boot Camp creates that is around 180-200 MB in size. Again, we can't stress this enough: this is done at your own risk - you are messing with your boot record and after this step, Boot Camp won't be able to adjust your partitions or blow away and reclaim your Windows partition anymore. Mac OS X and Windows will still boot just fine, but this isn't an ideal setup for the faint-of-heart Boot Camp user.
if you take the plunge and nuke that partition, however, you should now be able to boot from the Vista DVD and use it to upgrade your copy of Windows XP - which in and of itself could spark a discussion as to whether one should upgrade or install clean new versions of Windows; it usually isn't recommended with Mac OS X, who wants to take bets on Windows' ability to have a smooth OS upgrade ride?
If you try any of this stuff out, feel free to post your thoughts on the experience, and then go wash your hands of one of the dirtiest things you can do to a Mac.