OS:
i'm more partial to *nix based OSs. on PCs I will install Linux first and use it as my primary desktop environment then just virtualize Windows if I need to.
One of the best things about OS X is that it is
BSD based. Since BSD is very stable, you get fewer crashes on OS X. Although, I must admit, there are fewer BSODs on Windows these days.
Hardware:
if i have the money i will buy a Mac but i'm quite happy to use any other pc hardware. One good thing about Mac hardware is that because it is now Intel based, so you can now install and use any other OS on it (Windows, Linux, BSD/Unix, BeOS/Haiku) without doing any hacking.