just as a side note if it's of any interest to anyone.
I bought myself two new gfx cards to try out.
Sapphire X1600 PRO HDMI 256MB and an Asus EN7600GT HDMI
I tried them out with a HD recording that I've got of planet earth at 1980x1080. With my onboard gfx it was very stuttery. I've got a dual core 4200+ athlon with 2GB (dual channel) DDR2 memory.
Anyway the Sapphire card played the video quite smoothly. If you skipped into it a bit it took a few secs to pick up but the film was smooth.
I tried the Asus and it was still stuttering. Not as bad as the onboard gfx but still stuttering.
I would prefer the Asus card, but it obvioulsy isn't as good as the Sapphire. The Sapphire also comes with a low profile adapter so you can use it in a small case.
I then tried both with my 360 HD DVD drive in the PC. I am using PowerDVD 6.5 and when I tried to play king kong I get the HDCP error message. Both gfx cards were connected through HDMI and the TV is HDCP compatible so I don't know why this is happening?
I didn't bother trying it via VGA as I can get it to work using my onboard VGA connection.