I got a Vilano Shadow recently which is almost the same as your first pick. It's okay, it's fast, it's a mix and match of cheapest stuff they could get, unlisted shimano, dnp, etc and you *have* to be mechanically inclined to tune everything up, else you'd hate it and spend another 50 for tune-up. You'll spend another 100 for accessories, maybe 50 if you're careful. Also keep in mind that if shipping is included the bike is probably 50 bucks less in value.
I bet these and walmart bikes are made at the same Chinese factory, just different features, and to think that price of new bike in China is under 30 bucks!