MP4 to AVI and AVI files to AVI

[Gunny]

Ok you must be wondering what the second part of the file is doing there, but I'll explain later.
Now I have a Creative Zen X-Fi, which can supposadly support MP4, so I tried putting that onto it using my Micro SD Card, as it is the best way to do it, and it doesn't appear, which means the player doesn't support it. I also have AVI files which it can support, but some of the files frame width and height are to big, and the file sizes are massive, and I really don't want to take up extra room for no reason. So I need someone to guide me to help me convert these video's to AVI, which it can support. Now I'm not completely noob, but I'm not anywhere near advanced.
It supports:
Audio: MP3, WMA (DRM9), WAV (IMA-ADPCM) Audible4, AAC4, FLAC4 and the
Video: WMV9, MPEG4-SP3, DivX3 4/5 and XviD3 Up to 640 x 480 video size
I had the latest build, it had a bug saying that AVI and MP4 containers wasn't supported by the multiplexer, so I uninstalled that and installed the other build that I had saved on the computer 0.7.1.4486. If I could get second latest build not the newest one, that would also be appreciated.

(If you want to know why I use the Micro SD Card for some strange reason, here it is. To sync video's onto the player you have to use something called Creative Centrale, if the video is already in the right format, it decides it's going to convert it anyway, and that takes longer then media coder and does and does a shocking job, no other program can do it, as it only transfers the file and does not add it to the player. So I have to use the Micro SD Card, and have the right format on it, and transfer it to my player =P)

Thanks for your help =P