Of those original 8, 3 stand out above the others.
Hardware - Mac hardware is really not that great but it works. A simple tradeoff really, get the latest and greatest graphics card and run it on a unstable operating system or get one that's 6 months old that runs well.
Price - An entry level Mac is over twice the price of an entry level PC. You can talk about TCO but at the end of the day there's going to be a much bigger dent in your bank account at the end of the month if you buy a Mac.
Mac Uses - they're a bit like Christians, always telling people how wonderful the stuff they belive in is. I'm probably guilty of it a tiny bit but am trying hard to stop. I think its enough to say "I have a Mac, its pretty cool" but not add "you should really look into getting one".
FWIW, I don't agree with the comments about Vista. Infact I would say XP sp2 is great and many people feel that they are happy with what they have.