I have the same problem with TV card on win 7.I have avermedia super 007 tv card and used vista driver on it.it worked on vista normally before,but on win 7 there is also sound but no picture and just gray screen.and brightness ,contrast,hue tint adjustments are grayed out and cannot be adjusted.
guys try and see if you get anything with dscaler... i dont know if it works with win 7 but its free so you wont lose anything if it doesnt work
Windows update did it for me, i installed card, then scanned with win update, drivers loaded and working good