^Actually, the higher the res, the more gpu dependant, so at his lower res, it actually relies more on the cpu than it does on the gpu, your thoughts are reversed.
I'd say it will bottleneck but shouldn't be too bad, maybe 15% less performance than it should, It'd definetly help if you OC your CPU to at least 3.0ghz which should be pretty easy, OCing is safe as long as you don't put too much voltage and keep things cool.
Well I can't say you'd automatically get 100% if you overclock it, but as a reference I have a e6750 overclocked to 3.6 GHz and only on heavily threaded games (3 or more) is my CPU not enough. But that said, I'm hopping on the Ivy Bridge train next year because it's not enough for me.
If you get it to 3.0 GHz then you'll be good enough
The way to check is when you are playing a game and open your task manager and see if your CPU usage is at 100% or not. If it isn't then your GPU is being fed as much as it can handle.
Edit: Above is a bit of a generalization, but it's true most the time.
I think a new CPU will help you a good deal, but look at the e8500 and e8400 instead of the e6700, as they are clocked at 3.0 GHz and 3.16 GHz and would overclock to 4.0 GHz with not much difficulty.
Edit: Looks like the e6700 is clocked at 3.2 GHz, but I would still recommend the e8400 if you can afford it as it has a higher FSB and a larger L2 cache (helps with gaming a lot in the 775 chips). Try ebay maybe for a lightly used one.
Frankly, the socket 775 is dead and you would do best to upgrade to Sandy Bridge with a dual core i3-2100 or a quad core i5-2500k, but that may be outside your budget...
Upgrading old hardware is not a smart desition, you should stick with what you have and OC as far as stable, the e6700 is pretty much an overclocked version of the e6550, if you OC the e6700 it will be the same as your e6550 at the same clock rate (3.0ghz.), so you'd be wasting your money if you do that
well thnx to all experts.... u really helped me alot ....!
its done icouldnt get e8400 or above but i got a e7300 lightly used at same price as a new e6700 costs and it works flawlessly with hd 5770 ....... no need to oc !