I love my Harman Kardon system. You should be able to get all that you need for under $500. If you don't mind refurbished look here:
http://www.harmanaudio.com/
Right Now you can get the AVR 135 for $399 refurbished. You might have a hard time getting all 5 speakers for the left over $100 but you can add them as you go...
If not then look at J&R Music World, Amazon, Buy.com, Tiger Direct, Circuit City etc. until you find the best deal.
Other good brands are Yamaha, Onkyo, Denon etc.
You can look up reviews here:
http://www.avsforum.com/
I am not an Audiophile but I think Bose is terribly overpriced for what you get. Maybe not as bad as B&O or something but still too much. HK is a little high but they are really sexy and if you have a Mac I'm sure you appreciate nice aestetics.