If you want to do a subwoofer/satellite speaker system to get you close to the same form factor as the Bose look at those that j_garcia mentioned as well as Definitive Technologies, Energy, Paradigm, maybe even Klipsch.
If you do pick up one of these sub/sat systems it is likely you won't need anymore receiver than this one.
http://www.us.onkyo.com/model.cfm?m=TX-SR605&class=Receiver&p=i
It goes for around $400-$500 online and in stores.
What DVD player do you have now, what kind of display are you using? A DVD player upgrade depends more so on what display is used rather than the sound system. DVD players output surround sound to a receiver by a digital connection that pretty much 99% of DVD players have, you will get essentially the same top notch sound regardless of the DVD player.
It may be beneficial to consider in-wall speakers as well, if this is a permanent setup.
edit: I wanted to add this system as a very good wall mountable solution. The speakers are larger, but in all likelihood sound better and I know the subwoofer sounds better than most any sub/sat system in this budget.
http://www.us.onkyo.com/model.cfm?m=TX-SR605&class=Receiver&p=i