If by capture you mean via Firewire from a tape camera (some people do use the wrong term) then read below
I have NOT used either, but many say to try these for SD capture http://windv.mourek.cz/ or http://www.exsate.com/products/dvcapture/
I have NOT used it, but many say to try this for HDV capture http://strony.aster.pl/paviko/hdvsplit.htm