free software to convert video files to Xvid?

Hi!
I have a Toshiba TV with usb input for media playback.
Manual states that the following formats are compatible;
.mpg .mpeg .mpe and .avi
Any files I add with .Xvid work fine but any with the .avi extension WILL NOT WORK!
So, I'm looking for free programs to convert to Xvid.(not free trial, or any of the other crap I've come across)
Any thoughts on programs or any other ideas appreciated!

Many Thanks, Gary.

P.S. Manual can be found here.
http://www.manualslib.com/manual/321141/Toshiba-32bv501b-Owners-Manual.html?page=44#manual

Try this freeware AVCWare Video Converter: http://www.avcware.com/free-video-converter.html . It supports the converstion between multiple video formats, including most popular videos: AVI, MPEG, WMV, MP4, FLV, DivX, XviD, MOV, RM, RMVB, M4V, VOB, ASF, 3GP, 3G2, SWF, H.261, H.264, DV, DIF, MJPG, MJPEG, DVR-MS, NUT, QT, YUV, DAT, MPV, NSV and etc.