cabbitzilla

If you want to put Mac OS X on it, make sure it's got at least 256 megs of memory, and probably a larger HD than it shipped with.

Check if it's a revision 1 or revision 2 model: http://www.xlr8yourmac.com/G3-ZONE/yosemite/newfeatures.html

If it's revision 1, like my mother's, don't put anything else on the IDE bus that the harddrive is on. Get an IDE card and use that instead.

This tells you how to add extra drives to a revision 2: http://www.xlr8yourmac.com/IDE/add_2nd_drive/index.html

This tells you how for a revision 1: http://www.xlr8yourmac.com/G3-ZONE/yosemite/IDE/

And Accelerate Your Mac has loads more info: http://www.xlr8yourmac.com/systems.html#g3macs

Have fun!