We swear by what they call a Paper Tiger tool:
http://images.google.com/imgres?imgu...3Doff%26sa%3DN
It scores the paper through. From there, soak it down real good with mild soapy warm water...let that sit for half hour or so and the wallpaper will come off real easy. Once the paper is off, a good washing will remove the rest of the glue.
Yeah, they sell "d.i.f." as a solvent for undoing the glue, but I find warm soapy water works just fine.