After spending weeks and weeks deciding the set up of a new rig and planning on a HD 4850 with a quad 6600 vista 64 bit with 4gb and a DS3 mobo I talked to the guy in the small independent shop I was going to to have build it (I have 10 left thumbs and havn't a clue how to build) and he said the 4850 has a shed load of driver problems especially regarding older games and he would never get one. I have dealt with the shop before and not been steered wrong but now I am left wondering what to do and started looking at an 8800gt as budget is already beyond stretched and could do without the extra for an 8800gts. or a 9800GTX.
I do like some of my old games (KOTR, TOCA2) but i'ill be running my old rig side by side for a while so its not a massive deal, but I don't want to have to swap drivers on the new rig every time I play a different game.
One thing I will say is that they have had issues with some games because the ati drivers switch gpu/memory speeds quickly when moving from pure 3d to 2d menus (an effort to save power I believe). This causes crashes for some people.
I think older games get hit harder because some of them tend to have more 2d/3d flipping back and forth.
There is a huge thread about this on the ati support forums. I ran into the issue myself. I would constantly have crashes when I would go into my menus but it would work fine as long as I kept playing the 3d game.
What you had to do was manually manipulate a file and basically set it to always run at the same settings. That worked for me. More recently I tried the 8.10 drivers and haven't had a problem with them without having to make those changes. From looking at the files in 8.10 it looks like they set speeds constant.
So at this point I can tell you that I am not having issues anymore.