I would wait as the new 7000 series might be releasing as soon as november or so. Higher end cards might not be until christmas but your 5850 is good enough to last out until then.
I agree, BUT he already feels his 5850 is getting long in the tooth, if he wants to upgrade to the 6950 (not the best choice) that's up to him i advise atleast waiting until the 7000 series.Good advice but I think his 5850 would be able to last longer because recent games don't seem to be very demanding like they used to be.
A 6850 is going to be slower than your 5850. The 6870 is the equal to your 5850 (Per Anandtech Bench). You would need to go up to a 69xx to get any real gains.
That's why he said in the OP 6950 not 6850.
Overclock that sucka to 5870 levels (like i did with a bios flash) and then you get about 5% slower than a stock 6950.
unlocking a 6950 to 6970 is a whole different story though, so you might want to get a reference (not factory O/Ced) 6950 and pray it unlocks.