You have a system thats nearly identical to mine, except for the 7800gt so another alternative is to scour the MM for ppl offloading their x1900xt/xtx cards ready to get the next latest/greatest replacement. Theres gonna be some good deals shortly, so deffo worth waiting to see what comes up. Atm, you could get an X1900XT 512meg for around the £150-£160 with aftermarket and original cooler and an XTX for about £15-£20 more. A lot of these cards will only be a few months old so warranties would still be valid (though its worth checking that these are transferrable). And if you've only got a 1gig of memory atm, then get another also, lotsa games like 2gig, especially BF2, DOW, etc.

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It's the better card, ATI are winning this side of DX!