preview window is too dark

Hello
could someone please help me. I recently purchased a dv\tape camcorder it is a jvc gr d33u, I am using the latest pinnacle 9 software to capture the tape to my computer. My system specs is a 1 gig athlon processor, a nvidia 3 ti 200 with the latest drivers. My problem is that the preview window is too dark, I try turning the overlay control of my video card all the way up, but is still too dark. I can adjust the overall brightness of my video card and a preview window is OK but the rest of the screen is now too bright. And when I used pinnacle to lighten up the clip, and make a DVD the DVD seems to be to bright. What would be some suggestions to overcome this problem,
thank you very much