Connecting Speaker

[Ophelius]

Hi there,
I have a speaker I bought that I want connected to my cabinet. It's an 8 ohm, 15W mono speaker that I wish to connect to my pc output. So the stereo signal would have to be converted to a mono signal(both channels mixed into a mono signal, not the left or right channel only). I know I need an amplifier but I don't know much about them, but I know I probably don't need a fancy one. Anybody have any solutions for me? I've included a picture of the speaker for you. Click on it for a larger view. Thanks for any help.  

[Ophelius]

I think this would work well: http://www.dealextreme.com/p/60w-stereo-audio-amplifier-for-car-motorcycle-golf-cart-red-91350
I'm guessing I would simply use an adapter to convert the stereo signal from my pc to a mono signal and then plug it into the left or right input. Then I would simply connect the appropriate output channel to my speaker. The price seems too low, but I don't need great quality audio since my cab only plays old classic games.