ok seriously people are forgetting about Bootcamp, paralells and the lot.
Nowadays it's possible to run Mac OS X on Standard PC hardware and vice versa (although mac on PC isn't really stable, legal or supported) then there's always linux, but I'd wait until Ubuntu Feisty Fawn DVD (due mid april) release, hopefully by then beryl will be pretty solid as the developers plan to include it with Ubuntu, and if you look on youtube you'll see many videos of people showing off ubuntu+beryl emulating windows and mac whilst doing lots of other cool stuff
I would personally go with a PC if i were you cutegirl, mesh computers do some good PC's, if you really wanted tip top gaming performance check out some DX10 graphics cards, downside to this is by the time a DX10 comes out your graphics card will be outdated and stuff
Macs are great and can be fun, but quite a lack of games in comparrison, video editing is far more easier on macs (unfortunatley) and apple have their iLife suite which is handy for some.
Age old tech advice though, WAIT and RESEARCH.
Literally just around the corner there are DX10 gfx cards, Big name Software suite updates (Adobe, Adobe Macromedia, Autodesk etc) Apple Mac OS X 10.5 Leopard, iLife 07 blah blah blah
whatever route you choose (PC
) I hope you enjoy and utilize it to the maximum.