I was not happy with my TV card at first as well. (Terratec Cinergy 400) since my TV looked ok but the card was terrible. I found out in my case the cause was the weak antenna signal. When I employed an RF amplifier, the picture quality of the card became even better then on my TV. Apparently the tuner in my TV was better able to deal with a weak antenna signal.
The only problem with that is that it does not explain why your VCR looks crap too.
By the way: you do know that VHS will always look worse then TV, since VHS has a much lower bandwidth then TV, which means much less detail. A VHS cape will look blurrier and noisier then a good TV cap.
You could also try a DVD player for a clean and high resolution signal.