Yeah, it's hard to be with someone when you perceive them as "better" or more successful. You are probably a perfectly "worthwhile" person, but could use a boost in your opinion of yourself. Like mountainhigh said, you must have something going for you if she is interested in you!

Be careful not to let any negative feelings turn corrosive...there is always a potential that you could start trying to get in her way or bring her down as a way of "evening things out." Don't go there! Be supportive to her and yourself.

Good luck...she sounds like someone worth the effort...