Upgrading my 8800gt 512. Bottleneck question.

Hey there

Posted in the CPU section asking about upgrades. I no longer have the ability to buy a new computer at my years end  

So I simply want to ask some of you experts out there if you think ill see a performance boost if I upgrade my 8800gt 512 to a ati 5770 1g card.

Id also consider replacing my board and cpu for the same 220bucks id spend on the card if itd garner be better results.

Im running windows xp home.
2 gigs of Ram (512)
E6420 @ 2.12
the old p945 board socket 775 im using as far as i know doesnt really overclock.
The board is also so old im limited to conroe E6XXX cpu's.
native resolution 1650x1050

i can easily get a recognized 3 gigs in my system if a person thinks it worth it.

From the looks of things itll be the end of next year before i can get my new comp so Im hoping too squeeze some more out of this old paper weight yet.