I believe this one does require an AC, you may be better off going with a USB solution. It really comes down to what you are capturing. I have used a Pinnacle 801e for VHS capture with Virtualdub with good results.
As long as you are capturing SD, no problems with going with USB 2.0 or higher.
Yeah, I was going for s-video to usb and from reading these forums it was recommended to go for the ATI 600 USB or ATI 650 USB. The ATI 650 USB seems more prevalent. Couldn't see the Pinnacle 801e at all (on ebay)