I actually used Gadwin, but was still getting black screens with SLI. It worked fine when I had a single 8800GTX, but I remember when I had a pair of 7800GT's that SLI seems to cause some screenshots to come out completely blank.
Fraps seems to work, and I have a converter, so so far so good. Hell, maybe I'll even pay the $40 down the road. I totally expected something different than what Fraps really is. It's much more in line with what I want than with a lot of the bloat you can download these days.