I've heard great things about this lens, but I'm worried about the crop I'll get with using this with my 500D. With the 18-55 kit lens it's hard to frame things on the 55 side of things. Should I get a 30mm lens instead?

Ever since the 5D Mark II I've be drooling over a DSLR for a while. I've decided I want to buy the 7D* but I've heard multiple times that the sense that comes with it isn't worth the extra cash. I just want some good lens suggestions that wont cost a fortune but is versatile. I plan on getting the 50mm f/1.8 because I've heard so much good and the price is cheap but I want something that also has zoom when I need it. *final decision.