My 19" CRTs use ~60W each, so going with an LCD is cost prohibitive...
My old PIII uses ~70W at full usage, my Sempron64 ~120W, and the PIV uses ~160W. I just nabbed a C7 mobo combo, a serial receiver, and a gig of ram for ~$110 shipped, which I'm gonna replace most of what the Sempron64 and PIII do. Should pay itself off in a half year or so.