About a girl I like...is she interested???

I realize how old this question may be by now, but most women are a mystery to me. Anyways, I met a girl at a friend's house a while back. I liked her, but I didn't expect to see her again. About a week later, she added me on myspace and we started talking. I asked her out on myspace and never got a straight answer. I invited her to my house for a party, and she came with a friend (a guy). I completely froze up and didn't speak to her the whole night. Sad, I know. A few days later, she sends me a message on myspace and totally calls me out about not talking to her, but in a friendly, sarcastic way. I even got one of these :). I've texted her, apoligizing about not talking to her, which she was not mad about at all, and then asked her to lunch. Never got a straight answer, either that or she's busy. I think she's not interested, but someone else told me she's one of those girls that likes to be chased. Help...