Get a 260X, it's just a rebranded 7770 but with better clock speeds. Make sure you buy a good branded PSU, not a cheap one. You could buy a new motherboard if you really wanted but make sure you buy a 1155 socket motherboard otherwise your CPU won't support it. Your current board does only have PCI Express 2.0 and not 3.0 so your card will be limited there but not by a huge amount. I don't see much point in buying a new motherboard unless you're going to upgrade the CPU as well because it seems silly to buy an almost 3 generation old motherboard.