I am familiar with the Sony DAV-IS10 system. It seriously sucks in my opinion. Sure for $150-$250 it might be ok for a bedroom or something small, but for $800.00 it is an absolute ripoff. There is little to no midrange or actual bass to speak of with the system.
You could get a DCM Cinema 2 speaker package, basic upconverting DVD player, and a decent Onkyo receiver for that much and absolutely blow it away.