miloo: They're good for certain things. For example, I'm using an Acer Aspire one with the Atom n270... And I'm running fine with between 7-10 apps (1GB RAM, Windows7). Detectably slower than with my htpc build (e8400, 4gb ram, vista), but for work purposes, this definitely suffices.
I can definitely say that this thing could singlehandedly keep me warm if I was outside in the snow, though.