Mouse in Our House!

Monday night I fell asleep before finishing my homework, so, not surprisingly, I naturally woke up in the middle of the night to finish. Walking into the kitchen for some water, I saw a blob float across the back and down the side of the counter. I'm used to seeing spiders do this, but this blob was bigger than a spider.
Being the big girl that I am, I got a flashlight and started looking around the fridge where I saw the blob fall to.

I found a mouse standing on one of the wall logs looking strait at me beside the fridge!!!

I did not scream, but I did wake Peter up at 3 am to console me.
So, ever since Monday night we have found "evidences" of the mouse in more and more places. We've set traps with peanut butter, but nothing yet. Each morning the mouse (I certainly hope it's only one) has explored a new part of our house. I feel like nothing is safe. I don't know how, but he manages to reach all sorts of seemingly unlikely places.

So, how long should I expect to wait for this mouse to be trapped? Am I doing something to encourage the mouse to stay, or to stay away from the traps--besides the obvious and inherent danger of traps?