I selected my components with the help of you good people and built my system. That was a little while ago now. I have some cash and want to upgrade. I don't have any problem playing the lastest games and don't really have a particular reason for upgrading, I just want to. Is there any value in upgrading the RAM? (OS is Windows 7 64bit). Temps aren't causing me any problems but could still be better. I am getting way too much dust build up though and was wondering if liquid cooling would be the way to go. As always, very grateful for your suggestions 
Here's my current setup:
Intel Core i5-2500K 3.30GHz (Sandybridge) Socket LGA1155 Processor
MSI P67A-GD65 Intel P67 (socket 1155) DDR3 Motherboard - (Sandybridge) ** B3 REVISION
Sapphire ATI Radeon HD 5850 Extreme 1024MB GDDR5 PCI-Express Graphics Card
OCZ StealthXStream 2 600W Power Supply OCZ StealthXStream 2 600W Power Supply
Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz Dual Channel Kit (CMX4GX3M2A1600C9)
Seagate Barracuda 7200.12 500GB SATA-II 16MB Cache - OEM
Corsair A50 High-Performance CPU Cooler
Pioneer 24x Internal S19LBK DVD Rewriter including Labelflash SATA
BenQ G2222HDL 21.5" Widescreen LED Monitor - Black [9H.L3RLN.IBE]

Here's my current setup:
Intel Core i5-2500K 3.30GHz (Sandybridge) Socket LGA1155 Processor
MSI P67A-GD65 Intel P67 (socket 1155) DDR3 Motherboard - (Sandybridge) ** B3 REVISION
Sapphire ATI Radeon HD 5850 Extreme 1024MB GDDR5 PCI-Express Graphics Card
OCZ StealthXStream 2 600W Power Supply OCZ StealthXStream 2 600W Power Supply
Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz Dual Channel Kit (CMX4GX3M2A1600C9)
Seagate Barracuda 7200.12 500GB SATA-II 16MB Cache - OEM
Corsair A50 High-Performance CPU Cooler
Pioneer 24x Internal S19LBK DVD Rewriter including Labelflash SATA
BenQ G2222HDL 21.5" Widescreen LED Monitor - Black [9H.L3RLN.IBE]