Suitable CPU for gaming with a Radeon 6870 graphics card

I've been recently considering upgrading my computer, and there's a good chance I'll be getting a Radeon 6870 graphics card this year. What kind of CPU would I need to get the most out of that? I currently have an Athlon 7750 dual-core processor, 2.7 GHz, and I'm wondering if that's sufficient to make good use of that graphics card. If not, what you would you suggest? (Ideally something compatible with the 140W AM2+ socket of an Asus M2N68-CM motherboard, but I've also contemplated a motherboard upgrade at some point, so an AMD3 or Intel processor isn't necessarily off the table.)