does ps3 games uses dolby digital 5.1 or dolby true HD for its sound?

is Dolby True HD and DTS HD only for blue ray movies?
i don't watch blu ray movies so is it not necessary to buy a home theather set with dolby true hd and dts hd decoding function with 7.1 speakers?

if that's the case, i can just settle with sony DDW3000 5.1 home theather. Is this setup ok? anyone using it? what is its sound quality? is there better home theater set in the price range of rm1500?