[Windows Movie Maker] saving avi, not wmv, and without changing resolution?

[phabian]

I have a few .avi clips in 704 x 576 format, imported them in Windows MovieMaker v2.1 and created one big movie.

Now, I want to save the result. But somehow it always wants to save as wmv, in 720x480 resolution. I just want to save it as a normal avi (using ffdshow encoder) and I *certainly* don't want to randomly change the resolution! (because going from 704x576 to 720x480 will cut off content and/or stretch it out of proportion)

How do I do this?

When choosing File -> Save Movie File, My Computer, it seems to insist on saving a 720x480 wmv file, or do I miss something? When choosing DV camera (I've read something about DV-AVI), it says "your camera is not connected" - well I don't even have a camera whatsoever, I just want to save a .avi file to my harddisk.

I hope someone can help me, thanks a lot in advance!