There are some files here that are not transferring properly. When you try to download it you get a string of gibberish instead of the file itself. If you're just right clicking and using Save Link As that might be what's causing you problems.

Can you give us specific examples of AddOns that you're trying that aren't working so that we can give you specific instructions on getting that one installed?

@DeadEyez: Yeah, it is happening with FireFox 2. I don't wanna upgrade though hehe