Help with lens purchase

Since there seem to be a few camera pros on here I was hoping someone could help me with a lens purchase decision.

I currently have a Cannon Digital Rebel and I am looking for a good lens to take portraits and up close & personal shots. I have heard from a few people that a 50mm lens is good? Any thoughts, tips or comments are appreciated. My budget is around 400.00 - 500.00

Thanks in advance.