You have a few choices, such as upgrading your gfx card ( assuming you have an agp slot ), to one with VIVO which you can pick up, from ?70 to ?400+.
Or you could opt for a video capture card,( Pinnacle do a few decent starter cards ).
Whichever option you choose you should be given the neccessary cables to input your video.
Good luck with whatever you choose. Joe
P.s. I think it would also be a good idea to at least double your ram.