Was running Q9650 @ 4ghz with P5Q-E ,4gb DDr2 and a 470.
Cooled and quietened the 470 by fitting the Zalman coooler - overclocked it to 480 speeds, which it's been running since fitting without problem. Nice small upgrade.
Then moved to i2500k + msi p76a-gd65 + 4gb g-skill ripjaw - now THAT is an upgrade. No hesitation in recommending , without a doubt the most noticeable improvement in general performance I've seen in years and quite a few (what I thought were) upgrades. AND this was before I overclocked at all (now running at a nice and cool 4.2)
If I were in your position I would :-
1. Cool and clock(which you have - my apologies!) the 470.and
2 Either:-
a) Wait and see what buldozer brings to the table
or
b) Go for the Sandy set up - I'd probably swap my board for the newer z series and ,maybe (have not seen enough imfo. to give a reasoned call), get some slightly quicker ram.