Thanks for all the information everyone. For now I picked up 16 gauge oxygen free speaker wire from monoprice (16 since I don't have to run it very long, only about 5 feet right now for the fronts), connected the bare wire to the infinity speakers and used banana plugs to connect the receiver. It sounds fine so far I'll give it a week and see how I like it.
I continued by researching a little more on subs after the information you guys provided. I think I'm leaning towards either the build your own model the JohnnieB suggested or one of the 12 inch subs around the $200 range. Specifically the Polk PSW505, the Klipsch 12-HG Synergy Series, the BIC F-12, or the Dayton SUB-1200. Does anyone have any recommendations or thoughts between these choices? Good, bad, or otherwise, I appreciate the advice.
Also I had a question about whether I could use the rear speakers (and maybe center speaker as well) from the cheap costco setup I had previously with my current set up until I fill in the rest of the holes with better speakers. From my limited research, using cheap or low powered speakers has the possibility of blowing out the speakers, but since I'm getting rid of them anyways I don't really care if they get destroyed. My only worry is whether it could damage my receiver at all. Any advice on this front would be awesome.
Thanks again everyone for all the help and advice!