ME was a last ditch attempt at trying to make more money from the DOS based systems market.
Unfortunatly microsoft had already named the new NT system windows 2000, and people were comfortable with OS' named after years, so that took of whilst ME didn't.
ME has poor, really really poor memory management, basically no driver support. You could honestly go through life having never heard of windowsME and it'd really be no problem.
Serously, if anyone wanted a DOs based system they'd really do better to stick with 98SE.