don't know what to tell you about the receiver/dvd. I do have to ask.. is your entertainment center of sufficient value that it can't be replaced ? similar quality seperate DVD and receivers from Sony (and others) could be had for a combined $ 500. I'm sure if it's matched to the TV, there may be some issues, but don;t be letting a $ 130 Sauder entertainment center drive you to more expensive, lower quality, and less-flexible HT equipment.
you might take a look at these speaker packages:
for $ 750- the Mordaunt Short 9 series package at accessories4less.com. MS is one of the better mid-line speaker companies. good speakers including the fronts, a great center, the surrounds and a sub
for $ 1,100- the JBL Northridge 10 series package at bhphotovideo.com. again, all 6 pieces using the largest floorstander in the JBL line and free shipping. If bought at Best Buy, the pieces would be over $ 1,700.00
for $ 2,200 go to the axiomaudio.com guys. they get some of the best reviews on the sites I visit. you can go with one of their bookshelf packages for quite a bit less.