if money is tight then five behringer 2030ps and a quality sub like an epik legemd should give a huge upgrade. it should smooth out response as well as blend together ao that sub bass isnt localizable and speaker bass is full and meaningful. make sure to use 14 or 16 awg copper wire and finally add a refurb reciever like a marantz sr 5003 from accessories4less for hdmi 1.3.
the issue with the bose stuff is that it is designed to impress with specific bose demo material in a specific bose demo booth. when you bring it home many issues end up really degrading your experience, althoigh luckily as a brand name the resale value means it won,t hurt too much.
check out
www.intellexual.net/bose.html to get a feel for qhy we think you cpuld make a notble upgrade.