Let's try narrowing down his choices down from 2,190,000 links, huh?
If you're okay with command-line interfaces, try ffmpeg.
Or you can try Mediacoder. Both are free. The Mediacoder interface is pretty straightforward, and the option sets are pretty good for advanced users...for Mediacoder, bump up the volume default by 15-20 db. I used to go with PSP Video 9, which uses the ffmpeg set, but Mediacoder really makes use of dual core and more recent PCs.