that's pretty much it, .avi can still be anything. the most common codec that avi's are done in if they won't play right off is DIVX, you can get that codec at divx.com.
nevertheless Rob's suggestion is a great one, so you should take him up on that.
Downloaded a Nimo DivX pack and now I can watch my videos, thanks guys. Gspot still says I don't have the correct codec after I can view it now though /shrug.