One more thing.
I have an eMachines 3240. For an old PC the motherboard looks pretty modern. What's the upgrade possibilities with this machine?
Intel GMA 900
Intel Pentium 42.66gz
4 SATA ports
What looks like a PCIe port. It's black and ha a little thing sticking out at the end
Would it accept something like a Core 2 Quad config or a GFX card?
You won't fit any core 2 cpus in a pentium cause they use a different socket. It could probably handle some older graphics cards like nvidia 7xxx series, not sure though without knowing the mobo