I use Vidomi. When I capture tv (usually Simpsons) I set my all in wonder to capture to mpeg2 (dvd). I plop the resulting 1.8gb file in Vidomi, trim the commercials, and 20 minutes later I have a divx file. Vidomi allows me to specify the output resolution, crop edges, and target file size. Using 2 pass encoding it usually gets the filesize within a meg or two.

If you're looking to encode to vcd or some other non-AVI/divx format... try TMPGEnc. It will allow you to trim, and you can apply filters (to reduce noise, ghosts, etc).

I only use Premiere if I need to do something more involved.

These are all free, and work very well.