Sony HT-DDW840S

I am a complete newbie when it comes to home cinema etc
I have a very cheap Nicam only 28inch widescreen TV and need to find out how the amp works.

First of all I would like some advice on the TV. If I hook this TV up to the amp I guess im right in saying that the sound will be of lower quality than DD5.1 etc Is this right???

Also I would like some recommendations on the above amp/package, ie is it any good?

I was thinking of getting the next amp up in the range the STRDE685 instead of the STR-DE585 that comes with the package. Cant see much of a difference though??

Be nice if I could go for the 1080 amp but money cant stretch that far

I would also like to know if the amps come with dd ex.....whatever that is...It does have something called Cinema Studio EX (if that is the same thing I dont know)

Anyway any advice is greatly appreciated.