Hello, I have just upgraded my old Radeon x1950pro (great card by the way) to a new Sapphire hd 6850 for 99 euros (with Dirt 3 and Deus Ex human revolution included!!). The card is just great. My monitor is 1680x1050. You will be fine with most games, but remember that, for games, the faster the better. If I have had a more powerful PSU, I would definitely have go for a Radeon HD 6870 (which was 30 euros more) that is in my opinion the best bang for the buck you can get these days.
Which is your CPU?