As for ram, chances are the cheapest old ddr2-3 will be the most useful. Also, if you really want the last bit of juice out of your core2 system read up on the linustech overclock guide for LGA775. basic tips on how to FSB your way to greatness. if you can get a core2 quad near 4 ghz and cold enough to be stable, that will actually do for gaming.
https://linustechtips.com/main/topic/232325-lga775-core2duo-core2quad-overclocking-guide/