The programs that are mp3 are viruses. O.o
There's a few utilities you can use to open ZIP's on a mac. One being Mac's own archive helper as the image below shows. Stuffit Explander can be handy too. Some zips might be corrupted, or pc viruses. Obviously a program is going to be larger than 5 MB (5,000 KB) in most cases.
Opening a zip should normally be as easy as selecting it & Command (apple) key & O for open. But do NOT try to open ZIP's from within LW. Keyboard shortcut:
⌘ O