I was just given a g3 clamshell 300mhz and have been to multiple forums and even more memory sellers.For the life of me I can't figure out what 512mb ram will work with my unit if any.I am trying to go on the cheap since as a grad student I am flat poor.Also will the 300mhz clamshell take a combodrive from a later model clamshell.I am completly new to mac and this has me very stressed an confused please help.