You already asked this here: https://www.techspot.com/vb/topic145552.html, try to keep it to one thread.
Anyway, yes it is and I personally don't think its worth upgrading your processor, nor buying a gtx 480. Probably be cpu choked either way.
You wont see much performance increase with a core 2 quad over what you have now, best you can do w/o upgrading many parts is buy a new video card, the choice would probably be determined by what max resolution you like playing at.