Hi. It depends on how much you want to spend. You can start with quicktime pro. The pro key allows you to export as mpeg-2. For mac a great software encoder is BitVice http://www.innobits.se/ or I'd look at ProCoder for pc http://www.canopus.com.
If you use a mac I wouldn't look much furthur than BitVice but there are loads of encoders about for pc depening on your needs. You could look at the help pages on http://www.vcdhelp.com