I use the Videora iPod converter; it works quite well and (most importantly) it's free. Find it
HERE. The format should be .mp4, I believe. If files are not showing up, you may need to add them manuallyI also have the 30 gig and use it while driving my truck to listen to music, Spanish lessons, tutorials, etc... It's amazing. 8-)
To add files to iTunes, look here: