I wish I could ever find this page on the WWW again (archive more than likely?).
I used to be fan/nerd about #LTSP / #K12LTSP from 2001-05 and I remember clearly one build log/write up from some nerdy Linux school admin at the time. (Now known as #K12Linux)
They built with these specs that I can recall:
-TYAN mobo w/support for and installed dual AMD Opterons (single core)
-pretty sure they used horrendous Thermaltake Xaser case (or some chieftec/Antec SX clone).
-I forgot the HDD/RAM config