Seriously. Take the 32MB SIMM from one of them and put it in the other. The performance jump will be far more than you could hope to get from building a mini-cluster. If one of the cases has an open bay, you can even scavange the HD from the donor and set it up as a slave.

Heck with 64MB you should be able to run a GUI just fine even on a 486. Go for one of the lighter-weight ones, not Gnome or KDE.