I agree with effortless about Win ME. Do yourself a favour and upgrade to XP!
I leave a WinXP system on 24x7 and have zero problems - can go for weeks without needing a reboot, and then usually only if a Windows Update or application install requires it.
Not as robust as some Novell servers I knew that ran for literally YEARS without re-start, but not too bad - and a lot better than pre-Win2K.