279 isn't bad, but there's better. It's on pricewatch for 253. You might want to check out pricewatch, there seem to be alot under 260. You could probably get it shipped for less than 279.
As for the overclock, it's hard to say. What do you have for ram, mobo, HSF? w/o that info i would say maybe 1.9? with only air, and that may run a bit warm, with some good coolin, 2.0 shouldn't be far off.
And if you wanna stress test it properly, try Folding