Upgrade or not?

So I was thinking of upgrading my 4gbs of G.Skill PC6400 to 4gbs of OCZ Reaper PC9600... Would it be worth it? Or should I spend my money elsewhere... Specs are in signature

That seems to be the slowest part of your computer.

You wont see a huge performance gain from upgrading memory. I for one do not see the difference between DDR2-800 cas4 and DDR2-1066 cas5, benchmarks do though. And maybe some games gain 1 or 2 fps.
But your Gskill should be able to run near the speeds of those OCZ reapers if you change the timings to 5-5-5-15.

I don't think you'd notice a difference in real life scenarios. I have gskill ddr2 1000 2x2gig rated at 5-5-5-15 timing and I run them 1:1 @ 800 4-4-4-12. I noticed no real difference then running them @ 1000 5-5-5-15 or even @ 800 5-5-5-15, I just like 1:1.