The problem with Blade-PC's is the fact that they are a PC, with applications with huge memory footprints. When I last used X-Terminals in anger, we had a ratio of about 10 X-Terminals per (not very big) server, and because the software was not PC based, we got reasonable performance. Add to that the fact that you can beef up the performance by adding dedicated specialist servers elsewhere on your network that work just as well as the controlling server in delivering applications. Real distributed computing.

Sun once said "The network is the computer", and I believe it to be the case.

BTW. The AT&T systems mentioned by Brett were called BLITs (Bell Lab Inteligent Terminals) 5620 and 630 (and I know that there were later models) which worked over serial, proto-TP-Ethernet (called StarLan) or full blown twisted pair Ethernet (later models). They ran a proprietery OS that was probably called Layers (my memory fades), and allowed windowed dumb terminal, or locally run, downloaded applications.