I justify spending an hour on this today since the setup makes it more convenient to test web pages in different browsers on different operating systems: Parallels 3.0 running Windows XP and Ubuntu Linux within OS X. Windows XP is also good for downloading endless Windows updates and Ubuntu is good for making me afraid to install any updates whatsoever. (Probably not actually an issue for Ubuntu, but when I ran Red Hat linux several years ago, every fifth or six package install or update would give me a kernel panic that ended up with me wiping the hard drive and reinstalling.)

Parallels 3.0 is here ($79.99 or free, two-week trial); Ubuntu is here; you need to scavenge your own copy of Windows. Installing Win is covered in the Parallels documentation; Ubuntu installation to Parallels is covered, more or less, in a tutorial by Simplehelp here (Ubuntu install kept hanging, but after four or five tries it suddenly worked. No idea why. Which more or less summarizes my level of linux expertise.)