Simple answer, dont go with the easycap/whatever the else its been renamed as. I used to use one and it was a pain in the arse and had a number of problems, audio being the main one.
If you want to get something reasonably priced, look into the original HD PVR. You can pick one up for about 50quid now in a used condition, thanks to the PVR2 and Elgato coming out which has brought the price for the original one down.
I still use mine for all my videos, and to be honest, despite the temptation to get an Elgato, I will continue to use it until it gives up the ghost.