Check out Denon's pre-configured systems with boston acoustics speakers.

[Link: usa.denon.com]

they are a decent start if you want actual 5.1 surround sound - but you will eventually want to upgrade to a better set of front speakers and a more robust AV receiver...but either of those items will take most of your 650 budget.

if you are set on a 2.1 system and don't plan to upgrade for a while, get a decent set of starter bookshelf speakers (200-300) a starter sub (150-300) and a decent starter 2 channel stereo receiver (entry level yamaha/denon about 250-300).