Newbie

Hi i have a ps2 and have a budget of £500 for a sound system,i want 6/7.1 dts or pro logic, but i cant find the specifications of the models anywhere,most magasines just give and outline.
But what would be the ideal system for computer games/dvds/tv/radio/cds,using my ps2 as the server?
I dont mind between a seperate or all in one system but the seperate amp would have to upgradable to 7.1 sound so i can build on it later and the package would have to be 7.1 straight of unless they are upgradable too.
I want to know if my budget is abit extreeme for what i want at the moment,if so how much more should i be looking at and how much more beneficial is a 6/7.1 system compared to a much cheaper 5.1 system which would be more affordable to me.

thx for ure time
Tim