I wasn't taking about the RAM. But thanks!
I was thinking of fixing her up for my parents to learn about the computer. They are learning so speed isn't a factor.
Well, the only fault that makes any sense if it's the mobo is the RAM slots (not necessarily the RAM itself). There's no way to fix that except for a new mobo. I think that no matter what it is, that will ultimately be what you need to do (either that, or a new CPU, but the mobo is cheaper, so the best "first" option).
If you think buying a new mobo and possibly new CPU is worth it, then you're more than welcome to do it, but I
Even the cheapest system you could find currently would accomplish teaching your parents about computers and do it MUCH better.