What you have in the PC you are selling is a first gen Core i7 CPU. Now there are second and third generation i7 CPU's that use a different socket 1155. There are also the sandy bridge E i7's which use another different socket which is a more expensive platform. Ivy Bridge I7 would be decent I guess and the best sort of motherboard that have overclocking features are the Z77 chipset models.
Everything still uses DDR3 memory