I only have a Athlon 64 3700. I cannot play 1080p H264 files without severe stuttering and lip sync issues. I have the same problem with BD and HD-DVD's (LG BD/HD-DVD ROM drive). I have been told I just need a graphics card. I am using Geforce 6150 onboard atm. I don't have a lot of room so a small one and cheap as possible is needed and would prefer to stick wih Nvidia.