I just bought a used IBM thinkpad 600x

[hypermikem]

it has 128 mb ram and is 500mhz. WHat is the most stable and reliable operating system for laptops?

 

[Phantasm66]

at that spec, win2000 pro sp3.

 

[Rick]

Yes, Widnows 2000 is great. I would not recommend XP unless you put more memory on it and you are confident all of the hardware is supported.