DV is a codec, but AVI is a container; you can save a DV video stream in an AVI file. You need to find out what codec your camera uses; it's probably based on MPEG-4 (such as DivX, or XviD).
You can try the video encoding utility
transcode. It has a
wiki page for documentation.
Transcode has import and export modules for various codecs including DivX and DV. Caveat: transcode may not support the codec that your camera uses.
Alternatively, you could try
Mencoder but I am not sure if it has DV support.
If these commandline utilities are too difficult to use, you might want to try
Video Encoding Script Creator (VESC). From the Freshmeat description, VESC is "... a GUI for easily creating video encoding scripts. The scripts that it creates use other free programs (such as mencoder and mjpegtools) to encode video streams. VESC offers an easy way to encode videos to newbie Linux users." However, it is in alpha stage, and I have not tried it myself.
I have not tried converting from AVI to DV, so unfortunately I won't be able to help you further without doing some trial-and-error myself.
