Similar advise to what I've given.
If you've been longingly staring into her eyes and shes been staring back she clearly likes you! Ask her out mate it'll help you and if you get rejected then you can move on and stop wasted your time with this one girl as there is a fucking lot of them out there :). Start by asking her out on a date (go to the cinema, eat out or even jam in the park with your mates lol) .. even through msn if you have to... if you dont have her msn get it! But, move quickly as I'm guessing your at that age where relationships start out of no where and I fancied a girl once but, didn't have the balls to tell her and she was gone!
so learn from my mistake and ask her out asap.
Living life in wonder is boring and can become a waste of time.. plus the anxiety will build up the longer you take to do it. Why dream when you can make it reality?
~ Matt