I would get on 6950 now, and then another in the future.
This is the best 6950 out there at the moment:http://www.newegg.com/Product/Product.aspx?Item=N82E16814102951&Tpk=6950%20toxic
It has been confirmed unlockable by the reviewers of the card. This means you can load the BIOS of a 6970 and unlock the extra shaders that separate the 6970s and the 6950s. Most of the cards that have this ability have been replaced by non-reference designs, but this one remains.
It also has a pretty solid factory OC