Want to upgrade my speakers for pc/tv

At the moment I have a surround sound set from creative/csw. Its the DTS3500 (5 speakers Sub and Amp) which I use for my Pc and Tv. I connect to my pc via a Audigy 2 Platinum and to my Tv via my playstion 2 using the optical connection.

I have about 600-700 to spend on new equipment, can anyone recommend me some upgrades?

[alextgreen]

700 hey? This is just based on parts I like: Marantz 4200 @ £200 (still a few left if you hurry), Mission M73i (180ish) Mission M72i (150ish) Mission M70C1 (100ish) and a chunk on cable using your PS2 as a DVD player.