I think that if you like Macs and you happen to have a PC for whatever reason (maybe you realize that Macs have limited game playing potential) or if you're interested in getting one, then this might be a good little program to use. I haven't used it myself, so I can't attest to its stability and reliability. You're obviously taking a risk (probably a small one) by changing how your OS looks and feels.
From what I've read, it doesn't change your compatibility with anything, it just changes the frontend of your OS. It's a mask, more or less. So while it'll look like you're running MacOS X, you'll really be running Windows XP, just with a different cover on.
Now you might ask, "Why in the world why I want to bother with this? This sounds stupid!" Well, if you hate Macs, then yeah, it might. But Macs really aren't bad machines. Oh sure, the iMacs suck, but the higher-end computers (like the G4's and G5's I've worked on in the past) are pretty good. Are they better than PCs? I don't think so, but that's my opinion. I'm sure some die-hard Mac fans would say the opposite. Anyway, as I said before, this would just be useful for testing out how a Mac operates or useful if you prefer how MacOS runs and you have a PC. Otherwise, it's really of no use to you. Still...even if you have no use for it, you have to admit that it's pretty cool that someone actually engineered this. The website that's been created is pretty cool too---it mimics MacOS X.
Here's the link: FlyakiteOSX