Oh well, thanks for the advice, ya'll.
Went down to my FLMnPCCS [friendly local mom'n pop comuter chop-shop] and showed the owner Carl this thread. He agreed with everything Azul said. Told me I'd be throwing away my money to put any more money into my machine. Since everything I put in it is uncompatible with newer machines, it's really a waste.
Bummed. Carl was pretty sad, too. He wanted my $200. But he's an honest man, at least. Maybe someday when I can put together 6 or 7 hundred bucks, I'll let him build me a rig.
Someday. A long time off...