I'm with peris, buying top of the range stuff is a fools game, always buy mid-high range and you get bargains and yeah maybe you are always a couple of games behind playing the latest title on high, but if you really want that it would be cheaper to buy a 360.
My most recent gfx card (8600gt) was £70 2 months ago, which IMO is staggeringly cheap compared to what I've paid in the past. It solved all my woes and I can play all the games I want (Source games mainly) on max. I'm never gonna pay over £100 for any piece of hardware evar again!
Deads be aware you can get a PCI-E mobo super cheap (mine was < £50) and make the small leap to a decent card. I had a 6600gt agp card before and it was wank.
Highly recommend http://ebuyer.com - good place to read customer reviews and sniff out which are the best value for money (even if you then buy from another site).