Which component s to upgrade?

I would like some feed back regarding my system and where I can get the most bang for the back in upgrading my components. What would you change without breaking the bank. I currently have the following:
HK Signature Series 2.0 preamp
Acurus 3 way x 200w for center and rear speakers.
Acurus 2 way x 250w for front.
NHT 2.5 front.
NHT SC1 Center
NHT Rear.
Assume my cables/interconnects are decent/good.
65% Tv and Dvd/35%audio.
I'm getting a new Sony rear projection and the new Samsung DVD player with DVI out soon.
Your suggestions are appreciated.