It all depends on what you want to accomplish, and how much you are willing to spend. There are good models from Yamaha, Denon, Onkyo, Marantz, and Pioneer.
If you are just wanting digital sound, you might want to look into one of these very affordable receivers for now, use what you save for the TV, and then come back down the road for something more substantial.
At under $200 shipped, either is a good choice and will serve you pretty well if you been living with ProLogic all these years.
http://www.ubid.com/Yamaha_HTR-5940__630_Watts_6.1Ch._A/V_Home_Theater/a11036057.html
http://www.ubid.com/Denon_AVR-587_525_Watts_7.1_Ch.AV_Home_Theater/a11036056.html
http://www.accessories4less.com/cgi-bin/item/ONKTXSR504B
A couple of steps up would be this one for under $250 shipped:
http://www.ubid.com/Yamaha_HTR-5960_805_Watts_7.1Ch._A/V_Home_Theater_Receiver/a11036058.html
If you want to get more serious than these, let us know and we can post to match.