Bicycle tires do not work in the same principles as car tires. You want to have as much contact with the ground as possible, even in the wet/raining weather. I know it might sound counter intuitive at first, but you simply aren't going to be going fast enough to hydroplane or loose control unless you are really really going fast. Stopping may be a bit harder because of the wet rims and ground, but you will have the same problems as if you had non-slick tires. Tire skidding and etc, you'd still want as much tire touching the ground as possible.

As for the whole BSO thing; As you as you know what you are getting. I know a lot of people look down to them but they do at least last a year, at least from my experience. Cheaper in the short run, but I think if you had to buy a new bike every year, the costs stack up more than initial cost of a 'good' bike. You don't have to get new too, plenty of 'old' models in LBS' they are marked down. Not trying to tell you to not get one of those BSO, but as long as you know the facts and decide on your own, more power to you.

I would not recommend craig's list since they are all used bikes, and I don't think you'd know if someone was trying to sell you a really ****ty bike.