I purchased a cable over the internet that came with 5 plugs, presumably for HDTV, .... (really, to hook up our wii). any way to make this work?
If this is something like you bought Wii HD video cable
then that is a component setup. Red Green and Blue for video and the Red and White for audio. You need to have a red, green and blue video input and red and white audio input on the back of your TV.
If the inputs on the back of your TV are Yellow, Red and White only, as I presume, then you have composite inputs and the above component cable will not work and hate to say you bought the wrong cable. Hopefully it was not too expensive.