just imaging ...
can you build a hierarchical system ?
many dumb X-terms (x-servers) ...
several idendical application server
(maybe sharing the same hd image via high spped nfs mounts)
(addresses with the same ip with RR dns, or on different LAN to pation traffic)
a "big" file (mail, http, database) server backend,
accessed only by middle tier machines?
more scalable ?
.