I think I got this right, so just please let me know if I'm wrong in any retrosect.
My Dad has a C2D E2140 (775), Some Gigabyte board, 4x1GB DDR2 (think its 800), An OCZ Vertex 30GB SSD.
I have another computer that I barely use. I can easily swap it. It has a i3 2100 (1156), ASUS P58H67 M PRO, 2x2GB DDR3 1600, currently has a OCZ Vertex 60GB SSD, but I'll just transfer his SSD.
He's running Mint Linux 17, so no really need for a larger capacity since he's using only 1/3 of it. So swapping hardware will not be much of an issue here.
Now, if my "mind" is set right, that i3 and DDR3 should kill his E2140 and DDR2 10x, right? I've been thinking long about switching out parts.
Also I might swap my Radeon 5770 with his GTX 8800. (IIRC) This should also give a whopper boost.