I am having this same problem. (Windows 7)
That .rar is for the exe. I tried a .exe extractor, and was able to extract the files into the mods folder, but I get a crash to desktop when loading maps. I read that it may be due to files missing, but I think everything is there. And interestingly I have found that I cannot run bf1942.exe in compatibility mode earlier than Vista, thinking that could be a fix. Anyone have any more ideas?