you can get a phenon ii 955 and overclock to 970 (or just as high as the 970 would probably overclock) or get the 960t which is a x6 core with 2 disabled. with the right motherboard you should be able to unlock it with the press of a button or you can keep it at 4 cores and overclock higer for gaming. Look at some asus AM3+ boards!
Scan.co.uk is an excellent source for parts.
And that 960T is great value.
You'll probably get higher OCs with four cores than with the extra 2 unlocked unless you get lucky.
-> Take the higher clocks and four cores over six and lower clocks.