Hellknight, your current system is pretty much up to the mark and there is no need for upgrading apart from the GPU and PSU. Wait untill the Sandybridge E or AMD Bulldozer hit the market.
For PSU, my pick is Corsair TX750 V2 @ 6.2k, can easily handle the most powerful single GPU card like GTX 580. Multi GPU setup for higher-middle end GPUs are also possible.
But my pick is Glacialtech 950W 80+ Silver Modular PSU, available @ 6K in smcinternational. If you buy this baby, you don't need to think of anything for next 5 years, no matter how power hungry components you add. Only cons is it comes with 2 Years of warranty.