LGA 775 has tons of options, that socket was used for everything from later model Pentium 4's up through some of the fairly recent Core 2 Quad's. You'll have to do some research to determine what your board will take, and it may need a BIOS update too, but if possible I would look for an E8500 or E8600 for a dual core solution, and maybe a Q9500, Q8500, or a Q6600 for a quad core. You can find them relatively cheap used and new on ebay, amazon, etc...