I started out using Pinnacle Studio as it came free with the video capture card I bought a while ago. It is very good but I gave up using it when it started crashing quite a bit - I did author about 20 DVD's with it though. You could buy a video capture card just to get the software and then chuck the card, or you can buy a boxed copy for about £30-£40.
I have now moved on to Adobe Premiere Elements which is much more robust and has much deeper features but is a lot harder to get to grips with, but worth it once you have learnt how to use it. It is pretty good value at around £50-£70, can't remember exactly how much.