New Cyclist,
Take the Wal-Mart bike back. I've been a mechanic on bikes since the mid 70's and work a bit in our local co-op. North side Chicago should have a couple of co-ops available to you, so look into that. I did a full restore on a Giant Hybrid bike this last spring and it sold for $200. The guy that bought it was ecstatic that he found a good bike for a great price. He commutes to work every day about five miles each way (and he looked me up to thank me for recommending that bike to him). His first bike was crunched in and auto accident that left him bruised and battered but he got back in the saddle with the Giant and loves it. The co-ops are generally a great deal for cyclists. Smiles, MH