The big problem is not Microsoft' OS, but the drivers available for it. Since the MB's that you are talking about are new, then the manufacture probably will not supply drivers (Motherboard, video, serial, USB, video etc) for the older operating systems, hence they say XP and up. Chances are, your 'ME' might not work anyway. Fact of life... I know... I run WIn2000 on several boxes and I have some apps that will not run on them.
I just had to buy a video card for an old computer since Win7 required more video muscle than my motherboard was able to offer. Those things happen...
But don't let that stop you, if you do get that MB, I can supply you with XP (legally sealed, SP1).