| posts: 6,638 | Location: Wolverhampton/United Kingdom
in all honesty your not missing much really. My friend is still on LGA775 with a Core 2 Quad @ 2.3GHz and a 9800GTX+ with 4GB RAM and his PC can still play a lot of games pretty well. Hes just brought Lost Planet 3, Splinter Cell Blacklist, Resident Evil 6, and Batman Arkham City. His system handles them extremely well at 1080p with low to medium settings and using FXAA instead of MSAA. He uses DXTORY to cap some of them to 30fps to get a more smoother feel and neither of them dip below that 30fps mark and hes happy playing with a controller on his sofa on his 50" Plasma and the games look pretty damn good even with the lower settings.
If you really want to upgrade then I would consider saving up a nice chunk of cash and splashing out a completely new build, maybe save some of the stuff from your current rig like HDD, drives, case, etc. Get your self a Haswell build (4670K) with a decent overclocking board and an aftermarket cooler to overclock it with and some at least 8GB DDR3. Keep your current GPU as newer ones are JUST around the corner so buying a new one now would be suicide for your wallet as current prices will fall as AMD will release their 9000 series (being announced this month) and rumors are Nvidia have the 800 series ready for release early-mid next year so wait at least til then to decide on which cards to upgrade to.
If your happy with your current system and there is nothing that you want to play or do that it struggles or simply can't do then by all means upgrade. But like I said, my friend is still very happy with his £700 rig he build nearly 6 years ago if not longer.