I have an earlier version of this one:
MSI GTX 260 Core 216 (OC'd to 655Mhz)http://www.newegg.com/Product/Product.aspx?Item=N82E16814127430
The GTX 260 and the 4870 generally trade blows back and forth, depending on which game titles you're playing. So it's sorta 6 to 1, half dozen to another.
The other thing to look at, is what motherboard you have, and if you're at all interesting in doing Crossfire or SLI.