You didn't already buy the Bose speakers did you? Bose would be at the very bottom of my list for speaker choices. Generally speaking, their speakers suck imo, so it won't be hard to find better.
It's generally recommended to spend the bulk of your budget on speakers, then find the electronics you need to drive them. I repeat, I would never buy Bose. I would not even take a Bose sound system if it were given to me free unless I had absolutely nothing else I could use.
The
Affordable Accuracy speakers from Philharmonics are highly regarded here and should handily beat the Bose speakers. It wouldn't even be a contest. The Phils have very good bass for a bookshelf speaker and will work well until you can save up for a
decent subwoofer that'll put the Acoustimass system to shame. You'll have a couple hundred left over to start after getting the AA's.