Not able to open divX avi files

I can't open DivX avi movies...I tried the video with VLC, and the app crashes...and when I try with DivX player, well...I can't seem to install the DivX player, when I try to open it, it says some files are missing or corrupted...or something like that.
Any bit of help will be great!
FYI. I have an iMac G3, 400Mhz, 512RAM, OSX 10.4.

-Thank You

Try installing the Perian codec pack.

It works but very weakly, it lags a lot...is it because I have insufficient memory? I mean I have 512mb...or maybe my 8mb video card is the problem...What should I do?