Is he planning on keeping this part for a while? Does he plan on upgrading to the next version of Windows when it comes out(Longhorn)? Will he be using the video card to capture the video from VHS, or does he have a dedicated board for that? What kind of monitor will he be using?
For questions one and two, if he will be keeping it for a while and plans on upgrading to long horn, a cheap FX5200 would probably serve him well.
For question three, if he will be using his vid card for capture then an ATi AIW will be the better choice for that.
For the final question, if he has or is planning on getting a LCD at some point you will want to make sure that whatever board he goes with it comes with DVI out.