What video format should I use ?

[whoeverxxx]

I would like to find a video format that works with both an Ipod video and a RCA Lyra x3030 media player. MP4 files work on both but the sound is not compatable on the RCA Lyra X3030 when using MP4, just video.
I've been using CloneDVD mobil to convert my movie and TV show files for both of these but I end up doing it twice account of putting them in MP4 format for my wifes Ipod and generic (Divx) format for my RCA Lyra X3030 to make everything work on both units. Converting the same thing twice is a real pain.

Heres a link to the specs on my RCA unit.

http://shopping.yahoo.com/p:RCA%20Ly...NlYwNzaWJzcGVj
RCA Lyra X3030 Digital Media Player - Technical specifications - Yahoo! Shopping