So my computer is on its last legs but I cant quite afford the cool supercomputer that I want, my cunning plan is to buy a lower spec computer with easily upgradeable parts and add to it every month or so.

I was thinking about:

Intel Core 2 Duo E6600 (Would Athalon x2 be better?)
1 Gig of Ram (Easy to upgrade later)
2 x 7600GT 256 Graphics cards (Easy to upgrade later)
2 x 250 Gb Hard drives
Soundblaster SE 7.1 soundcard
550W PSU
2x DVD rewriters
Vista Home Premium

I'm hoping that would allow me to pay most games like MTW2 and I would upgrade the RAM to at least 2 Gig and the graphics cards to 2x 8800 GTS 320 Mb later. The whole system comes in at just over £800 and that is the most I would like to pay atm.

My main questions are am I better going with the Core 2 Duo E6600 or the Athalon x2 5200+ and is it easy enough to upgrade a processor later if I went with the E6300 and upgraded to the E6600, is a 550W PSU enough and the obvious question of Vista.

Any comments are welcome

Thanks