The 4850 is a great card - slightly better than my 8800 before it.
Hoever, in our family we've gone through two 4850's and two 4870's in the past three months - all have subsequently been replaced with nVidia cards. The Sapphire 4870 driver issues (yes not strictly ATI's fault) and the 4850's unreliability has really put me off. One of the 4850's has crapped out after just a few weeks of playing Barbie Horse Adventures on my 7 year olds PC - hardly a difficult task! Back to nVidia for me