Oops forgot this one:
I own a Dazzle* Digital Video Creator USB for my old PII. All it can do is AVI to MPEG1. It is no longer avaliable in the market.
The newer products are really impressive:
Dazzle* Digital Video Creator 150
http://www.pinnaclesys.com/ProductPage_n.asp?Product_ID=1426&Langue_ID=10
But now I don't use any of these. My P4 is fast enough to real time encode uncompressed Camcorder video to WMV9 via Movie Maker. I am getting near-DVD Quality. So no more extra costs for me.
It your choice after all,

McoreD