I have the 3850 AGP (Powercolor) on one of my systems and so far it has worked well. I knew when I bought it there might be minor driver problems, but I was willing to take a chance. I also knew it was a little overkill for the system. It has played the following fine.
Call of Duty World at War, Spore, Team Fortress 2, Portal, Half Life 2, Quake Wars. All on 1680 x 1050 Resolution at medium settings.
As far as driver issues and memory (get 2 GB) I do agree with TheGreatGrapeApe "When you find that mythical card you let us know." I've had a dozen video cards over the years and some were excellent (8800 GT, 6800 GT) and others (5600 LE) I wanted to throw at a wall.
Abit NF8 - V2
Athlon 64 3400 (2.4Ghz)
Corsair 2x 1GB DDR 400
Spire 500 Watt
Powercolor 3850
Raptor 150 GB