[markw10]

For the PC I have a suite of conversion programs by ImToo and Xilisoft which is basically a suite of programs to convert many media types any way you want such as mp4 to wmv, avi to wmv, wmv to avi, mp3 to others, etc. Basically you can convert any video or audio program between many formats. I'm not as concerned with picture formats since I think I can change these in Adobe PhotoShop and mostly just use jpg anyway.
These programs will also convert video to be uploaded to a ipod, sony psp, etc. These are for the PC now and since I have my first Mac I'm looking for something similar to this for the Mac. Any suggestions?

[TETENAL]

QuickTime Pro can convert video to those formats it natively supports. WMV is not one of them, so if you want to convert to this format you need something like the commercial version of Flip4Mac.

HandBrake can create videos in the correct format for the iPod for free.

[Curiosity]

iSquint can convert .avi files (and maybe others - haven't tried) to .mp4.