I had done it with my previous PC. I had a Hauppauge TV card which had s-video inputs and outputs. I also had a Leadtech video card (called ViVo-video in/out)which also had s-video in/outs. I don't remember which video ins I used. I also used some software to capture and digitize the analog image. I think the software I used was by Nero. There was no problem with resolution, but it was hard to find a software that worked smoothly and didn't pixelize.
Later, I have also seen some USB external devices (bundled with the necessary software) that claim to do the thing. I haven't used any of them.