WinZip is ok, but i suggest WinRar. its a lot nicer of a program in my opinion and it doesn't have any sort of trial only version. Plus it seems that WinZip doesn't read WinRar zipped files, but WinRar can read WinZip files. SO you can effectively "double zip" a file by zipping it with WinRar and then zipping that zipped file with WinZip. Of course the usefullness of this really only becomes measureable with large files to begin with.