A LGA 775 CPU (Like your core 2 Duo) will not work in a modern LGA 1155 Motherboard. However, you can pick up a cheap, DDR3 supporting LGA 775 Motherboard on ebay for roughly $40. IF you don't want to throw away your old CPU and want DDR3 support, this is the best option. http://www.ebay.com/itm/INTEL-CPU-Socket-LGA-775-G41T-M7-V1-0-DDR3-MicroATX-MotherBoard-/140890178658?pt=Motherboards&hash=item20cdb58462
However, it might be better for you to build an entirely new system, as you will get much better performance.