I'm 99% sure it's PC133 - DDR didn't come out until the P4.
If you ask around, or look in your equivilant of the Trading Post, you should be able to get another 128 or 256 pretty easily. The more the better, really.
Old PC's... By the time you've farted around with them, spent days looking for Drivers, etc etc you'd be better off building a new one!