GTS 450 or GTX 460 with an E6600

I currently have an E6600 OC'd to 3.0GHz. I want to upgrade my GPU in anticipation of Rift: Planes of Telara. I am trying to decide between a GTS 450 and a GTX 460.

I understand my CPU will bottleneck the GTX 460 and I will not be getting the card's full potential.

My question is will a GTX 460 in my current system outperform a GTS 450 in my system? Or will my CPU bottleneck the GTX 460 so much that the system as a whole will not perform better than if I had just stuck a GTS 450 in there instead?

Another factor that is making me lean towards the GTX 460 is that once I upgrade my entire PC I can use the GTX 460 in a new build. I realize I will probably want a new GPU when I build a new PC, but it helps justify the extra cost in my mind for now.