<< Just stay away from ME. >>
Yeah that pretty much says it all. While Microsoft will defend ME saying its the best the 9x kernel has to offer, for the most part it isn't true. WinME is basically windows 98 Third Edition. Microsoft included a bunch of..ahem "features" into ME that actually made it more buggy, unstable, and sluggish. My experience with ME is that it is an OS that can never be trusted, I would never, ever do productive work on an ME, for constant fear of crashes. Win98SE, IMO, is easier to get running clean and smooth, and most importantly, stable. The drivers for devices are the same for 9x/ME so you don't have to worry about hardware missing out on hardware, at least not for another year or so.
If you can't tell already my advice is to just stick with whatcha got. And if it's been a while since your last re-install, I would say go ahead. A fresh windows install is a happy windows install.
Hope that helps.