I have my pc hooked up to my 19" Sony monitor via VGA and also use the DVI output to connect to my 37" 1080pPanasonicHDTV and run the two together via dual monitor mode, monitor for pc stuff, TV for HD films etc. Both are set to different resolutions respectively and are both working fine.
The problem i'm having is when i come to play downloaded HD 1080 films on my HDTV, the film skips and jumps. This only happens for high def films, normal dvd rips run fine. I've tried setting my HDTV as my primary monitor to see if it made any difference, and also tried updating my video card drivers. Still no luck :(.
Anyway, i think it's down to my video card, the one i'm using at the moment is an ATI Radeon 9800 Pro:
Your whole computer may be too slow, not just the video card. From the CyberLink website:
"HD DVD-Video and Blu-ray playback requires a high performance PC platform. It is recommended that you use a system with at least Dual Core 3.2Ghz processors and 1GB RAM system memory. Discrete graphics solution is also required with at least 350Mhz clock rate with 256MB VRAM. (Check for detail supported graphics solution)."
The processor requirement seems a bit high though, my computer for the most part plays HD files quite fine with a 2.4GHz E6600. The only time things bog down is when I try to play mkv files set to 1080i. The CyberLink site also has a BD / HD Advisor program you can download and run. Once run it will tell you what parts of your system aren't enough to play HD stuff:
