system as I know of:
(upgraded) 40gb hdd
This is not my system but a friends at work and this system has run strong for 5 years with one minimal prob such as a keyboard replacement. He installed a second battery and the new hdd just a few weeks ago. I have to say, this machine is a powerhouse when it comes to how long its been around, being that it has not been in the most desired atmospheres (a carbide grinding shop part of the time) As money doesn't seem to be an issue atm, he plans to put a 1ghz in place of the 800 and wanted to know if video cards were swapable as well.