1.
WithMP3 -- It is in my opinion, the best MP3 app for PPC. I have been able to achieve much better sound from it (through headphones, external speakers, and the built-in speaker) after adjusting it's Equalizer than I have been able to get from any other MP3 player application.
2.
Pocket MVP -- This is a top-notch Divx player, and best of all it is free! The website is kind of slow, but hang in there.
3. A free version (OEM) of Resco Picture Viewer is included on the Dell CD that came with your Axim....so that should work fine for you. A newer version of this software is out, with many improvements and more features. Resco is giving Aximsite users a discount on the new version right now.....check out the Members Discount Forum (linked in my signature) for more details on it.