How do u tell the difference b/t a shy guy and one who's just not that into you?

A guy I like (22 yrs. old, but very successful, smart and financially well-off) seems shy towards me, but I may be mistaking "shyness" for the possibility that he is "just not that into me." He was too busy to talk to me one day and partook in some witty emails for awhile. Then he stopped emailing me. He offered to fix my computer for free and lent me a computer part for free as well. My friend said that this guy thought I was attractive. But he hasn't asked me out. Whenever I talk to him regarding the computer (in person) he is very busy or just doesn't start up a conversation outside of the realm of the computer. I am intimidated by him b/c he is 7 yrs younger than me and so successful. I'm successful, too, but not rich, yet. I'm just starting my career. He has his pick of cute, young girls to choose from. I'm very pretty, so ppl say and have a good personality, but can be very shy. I want to know if this guy is "just not that into me." If he's shy, couldn't he still conjure up the courage to ask me out or at least talk to me when I'm being friendly to him?