haven't tried it or read much about it but ecs makes a small p4 board similar to miniitx size, or perhaps the exact same size. it comes as a barebones with a case and psu and called the u-buddie. there are several models but the newest can take celerons or p4s i believe. i'm really surprised no one has discussed these before. i've seen them go for $150 or so shipped, which isn't too bad for all that you get.