Have a problem here, the machine is an antique by today's standards, but your real problem is twofold:
Eith 64mb of ram, nothing is going to work properly...and although you can probably still find memory modules if you look around...it probably isn't worth the expense.
With up to date pc's available cheaply, I would suggest you look around for one that you can afford...It need not cost an arm and a leg.
You could start here:
If you want to use your old monitor (not really advisable, as refresh rates have changed dramatically and many apps need higher resolutions) You could opt to buy a "box only" solution, but the saving would be minimal.
Good luck :)