Good upgrade for 8800gts?

Hi I've still got my 8800gts that I've had since I built the computer, think it's time for an upgrade but I'm completely out of the loop now.

What are the strong middle range cards at the moment and will they just slot straight in to my motherboard or has it all changed already?

Thanks.

Budget?

Under 200$

6870

over 200$

6950

HD 6870 is the best bang for the buck right now, but it requires 2 power connectors, not sure about your gfx. HD6850 (regular, non OC'ed models) require 1 6-pin connector.

Thanks guys.

What's your power supply?