Mammoth, Oh yes..you bet I am now!
Now that I know that it was just that darn card (ATI x700). You see, all this has just come about within the last 3 days, that is...me getting the new machine with the Nvidia 6600 and finding this thread, so now that I have put all the info together, I am slapping a 6600 in that other machine and possibly taking the new machine back. My older machine ran great, with the exception of switching inputs and getting a black screen when coming back to the MCE box (with ATI card), so I am definitely going to find a use for the other box, or possibly even take the new box back as I have a 30-day return policy on it.
The new box is pretty sweet, it is the HP z555 Media Center box, with LCD screen, etc... BUT when I pause live video on it and return, the video is super choppy...AND the box gets SUPER HOT, so I truly may be returning it and sticking with my old box! It has a 3.0 Ghz processor, 1 Gig Ram, Nvidia 6600, Hauppauge MCE500 PVR (dual tuners), HDTV Wonder, 2.4 Ghz wireless, etc., and with all that, the video playback on paused Live TV is pretty bad at the moment (it stops, skips, pauses intermittently) so I am definitely not going to keep it if I don't find a fix soon! (the old box never had those problems) 