If the core2quad and 710 is all you can afford, go for it.
I really wouldn't spend any money on an lga775 system with a core2 processor. They arent very powerfull, they are too old to support modern instructions to run new games, they have no upgrade path, but cheap at least.
If you buy something like an i3 2100 prebuilt you can upgrade to an i7 3770k which is still a powerfull cpu.