I have a HD3850 AGP on a XP SP3 system with a P4 3.2 / 2GB. It works ok, except for some minor issues with hardware accelerated playbay of WMV and h264 (but only when using ATi's decoder, Cyberlink works perfectly). I'm looking for a good guide to tweak it a bit so that WMV works as best as possible (currently only works by disabling post-processing with WMV Powertoy) and h264 HD playback is also possible with ATI's decoder (already got it from ~25fps to about 40fps using undocumented tweaks from ATi Tray Tools). I noticed there is a fair bit of information available for HD2xxx's, but no information how tweaks for those play out on a HD3xxx. Most tweaks are also for old drivers. I'm rather surprised that there is so little info on the HD3850 AGP and getting it to work as best as possible, since it is quite populair (for an AGP card).