I'm having a bit of a dilema lol

Fancy upgrading the PC, with gaming in mind.

Current spec -

Q9300 quad core
6GB DDR3
HD 4870 dual core GPU with 2GB RAM (IIRC)

I know there's little point changing to slightly faster socket 775 processor. So i was thinking about changing the Mobo and going for a socket 1366 i7? Most likely an i7 960 to get me started and probably 12GB of DDR3. Leaves me open to upgrade to a 6 core later on.

From a gaming point of view am i better doing this or spending the same £ on a new GPU?