Does this girl like me?

This girl is a friend of my roommate, I think they work together, but they also had a cl together. Well, she's been over our place a couple of times to study with him. I've noticed her looking at me a lot and one time she jumped on my friends computer and IMed me telling me to IM her so she'd have my screen name. We've been on vacation for about a month now and I talk to her pretty much everyday at least once of not two or three times, but she's so hard to read. I feel like I IM her a lot more then she IMs me and that kind of concerns me. She once asked me if I found her attractive and I told her yes of course and she told me she blushed, so I have no idea what to think. I'll be back at school soon and I'll see her for sure. She loves Mario kart so I invited her to play and she said yes, and seemed interested in watching movies and stuff, what should I do? Do I tell her I like her?