Run a search in Google for Virtualdub. You should get results showing different versions that people have come up with / added to the original. To see what codec your avi movies were encoded in do a search for a freeware program called "Gspot". It will tell you everything. I learned all I ever needed to know and a lot more from the site
www.vcdhelp.com and there is a specific one aimed at PPC called
www.pocketmatrix.com. Check out their guides and tools (Gspot should be there) sections.