well, I don't know man if your downloading like 700mb avi junk then it won't ever look like a dvd on tv. Now you have a decent monitor so that is just strange.
computer monitors have very high resolutions, so dvd's have to be stretched out to
fit full screen, which makes it look bad cause theres not enough pixels on the screen.
I had this problem too I download some HD trailers for WoW and Diablo 3
They looked awful! Very pixelly and choppy! I have an XFX 8600 GT also
I found out it was my video player I download VLC player and now they look great
(old player was windows media)
Let me know how your card turns out I was thinking about getting a new one also :]
well 4850 is just barely behind in performance and a lot cheaper (and doesn't suck so much juice). But how much gaming you looking to do and how big is your monitor?