Just buy a Mac. Seriously.
I've tried and tested it before. The background hacking you need to do with some apps makes this very unfeasible for anything beyond an experimental testbed. Frankly, I'd advise against even that unless you plan on running it through a virtual machine since the hassle of reformatting for an experimental operating system is really beyond what most people should want or need. If you run an AMD processor, you won't get the same quality of performance. Even if you run intel, you run the issue of bugs and small instability problems as well as the fact that you can never run mac update until a fix is posted.
If you can't afford a new mac, check the eBays of the world for a used G4 Mac Mini with at least a gig of ram. It'll do you some good unless you plan on running Adobe CS3.
If you need reasons to get a mac, go to your local Apple Store on a weekday morning or right as they open. Just sit down and play with the toys they have on display before the crowds rush in. They don't really impose any limitations on what you can/can't do on their demo machines.
If you need more reasons and want high power, don't forget that the Mac Pro is pretty competitively priced for an ultra high performance workstation. You can easily bootcamp that sucker and run a partition with XP / Vista in their respective 64 bit editions
