Any idea how to make this Zalman microphone work on my iMac?

I bought a Zalman ZM-MIC1 off Amazon as it has pretty good reviews and it very compact, which is what I was most interested in. Now, I was under the impression that I could just plug this into the back of my iMac and off I'd go. However, that has turned out not to be the case.

What it actually does, is nothing.

Now, I've tried my iMac running OS X and Windows 7 as well as my MacBook Pro running OS X. Neither machine was able to make it work.

The best I can get is that when I plug it into my iMac under Windows 7 the default audio input device switches from the built-in mic to the line-in port. I don't know if that means anything beyond the port isn't broken, however.

Any tips and tricks would be greatly appreciated. If I'm honest, I need to verify that the mic works at the least. However, what I'm eventually hoping to do is get it to work under Windows when I'm gaming.