What type of upgrade are you looking for? Your CPU is up to date, and your GPU isn't bad either, what speed boosts are you looking for? Gaming/FPS boosts or DVD encoding/video editing type etc. boosts?
well there is new hardware being released constantly.
ATI has recently announced their new generation of GPUs, but who knows when they will be released. we also have Nvidias newer GPUs coming out, which are expected to fix the heat and power issues many of the cards have suffered from.
CPU wise, the new AMD Hexcores have been released, and are very reasonably priced. but the next big thing wont be til bulldozer is released next year.
if you really want an upgrade, i would recommend grabbing a HD5850 for now, which would run fine with your current CPU. then see how things are going with the HD 6xxx series and bulldozer next year.
to be honest though, your current system is still quite capable. you don't need to upgrade. but i understand we don't always upgrade because we need too...