I urge you to use some steps on this. The first step I would take is to OC your CPU. MMOs can use the CPU power in most cases and if that 955 is stock that might be your issue. So grab a good cooler, one that carries over to a new system, and see how the performance improves. If you hit acceptable crowded areas then you just saved a ton of cash. If not, at least your new cooler carries over to your new rig.
This will also tell you what you need. If OCing helps a lot, but not enough, then you know you have a CPU issue and you need a new board and CPU. If OCing doesn't help at all, then you are still GPU bound. (I suspect you are both.) You can buy the new parts according to what you need.
I guess I should have added it is OC to 3.6 with the stock cooler. If I run it at max setting my cpu usage goes way up, but on high(what I've been playing at) it gets up in the 50-75% area. on the bench mark anyway. Maybe that answers my question lol. I wanna do both upgrades anyway but I can do one this week, the next in like a month or so.