I typically just use this for work stuff, but I occasionally play games like Starcraft II, MS FSX, Borderlands, Halo2 and a few others. It works fast and I really don't have any complaints about it, but I want to keep it updated.
What should my next upgrade be or should I wait a while longer before doing anything?
Wait. A c2q overclocked would help with games like SC2 in large battles, but if your performance is good enough now you shoudl wait for 6 months and let intel and AMD release their next generation of CPUs and ATIs next generation GPUs. At that point see what pricing is like.
If you really need to upgrade now, I'd look at either another GTX 260 in SLI (if the PSU can handle it) or a GTX 460 (it runs Starcraft 2 very well). With a potential GTX 490 around the corner, the 460s could drop in price...