As long as your motherboard supports it, shouldn't be a problem on the upgrade. Make sure you have the latest Bios before upgrading.
But actually, I'd say no to it being a large increase. There will be some increase, but nothing big.
Compared to intel what? The intel equivalent's are typically around the same price, maybe a couple bucks more. Since there is no AMD equivalent for the I7, thats why the I7 is much more expensive. The Phenom II quads can't even beat the I5 750. And actually the 1090T, AMD's newest hex core, barely beats the I7 in multithreaded apps but still looses in single threaded ones....but it's more expensive than the I7.