Question : Problem: which future-proof graphics card should I buy to play the latest games (e.g.Crysis, Far Cry2, CoD4) on my XP SP3 system?

My system specs are as follows:

Mainboard: ECS Geforce6100SM-M2 V1.0A (nforce 405 chipset)
Processor: Brisbane Athlon 64 X2 5000+ (2.6GHz)
Video: Onboard Geforce 6100/s VGA
Sound: Onboard Realtek ALC662 6-channel HD audio
Memory: Corsair TWIN2X2048-6400 2Gb kit
OS: Windows XP Pro SP3 (32bit)
Storage: 80Gb Sata II, 7200rpm; 250Gb IDE Ultra/133, 7200rpm
Power supply: Winpower 750 Watt (with +12v rated @ 33A)
The case I had previously and is mid ATX tower sized I believe...

I basically wanted a cheap entry level dual core system (this whole setup cost me slightly less than £100!), but gradually my eye has been drawn towards the eye candy games such as Crysis, Bioshock, CoD4, Assasin's Creed e.t.c.
Considering I'm not going to be updating to Win Vista until it reaches SP12 or 'round about (I'm not contemptous honest, lol) What is the best PCIe card I can/should get? I suppose I would like two options. One where money is no object and one where I had a max. budget of say ~ £100.
Any ideas? Cheers!  

P.S - will an upgrade to 4Gb from 2Gb help with these games in XP?

Answer : Problem: which future-proof graphics card should I buy to play the latest games (e.g.Crysis, Far Cry2, CoD4) on my XP SP3 system?

Though again the 9600 is the bargain basement "good deal" version.
for the "money is no object" that is a whole nother ball of wax.

But I will breakdown the numbering scheme and you can go from there.
the 800 line (aka 8800/9800, etc) is their gamer market items.
the 600 line (8600/9600) is their economy line
the GT is basically their midlevel of RAM

GTS was originally released as their gamer RAM, but with the 8800 line, the GT out performs the GTS due to a die shrink/performance enhancers. Basically GTS is released first, they tweak it, and release the GT.

GTX is their extreme performance line.

For money is no object, get dual 8800 GT in sli.
You want future proof, it will take more than XP or Vista can put out, to outdo that setup, especially if you go 4GB of ram and xp x64.

Oh and the reason I am not bothering to even mention AMD's graphics division, is I don't hate you, so I can't recommend them.