Do you think my co-worker has a crush on me?

We work in an office together; she works part time, so I only work with her once a week, having worked with her on 3 occasions. She's very friendly; so we get along. The last time I worked with her, things seemed extra friendly. I asked her for advice on a girl I was seeing, her advice was to stop seeing her. We took all our breaks, and lunches together. Which consisted of nothing more than us going for some fresh air. We sit only a few feet from each other, but I guess we didn't want other co-workers listening, so we chatted on MSN the whole day. Another co-worker mentioned that he kepted on hearing "awww"s and laughter coming from her desk. Also, she knows I write. So she said next week, she suggested we take a lunch, and go get coffee...and she would sing for me, I guess humiliating herself a little, if I'd let her read something I wrote. I like the flirting, but I think she's with someone right now. So I don't know if she's just bored at work and enjoys the conversation, or if she has a crush on me.