One option that I only recently became aware of that might work well in your situation is this Sound Bar system from Sony
. The cool thing about this, is that the subwoofer works much like an A/V receiver - it does video switching and analog to digital conversion of all sources to HDMI. This way, you can hook up your Blu-Ray, HD Cable/Satellite, game system(s), etc. and still be covered.
A drawback to this system is that should you decide to go full surround sound at some point in the future, you won't be able to make use of any of the parts of this system - it would at best be relegated to a bedroom or other smaller system, and you'd have to start from the ground up for true surround sound.
On the other hand, for $500, getting an A/V receiver that is at least moderately "future-proof" as well as even a 2.1 speaker system would be quite a challenge.