Linux Computer Systems
Linux Computer Systems supplies Workstations, Servers & Beowolf Nodes, from AMD K6 to Quad Intel Pentium II Xeon Servers. Starting at $675
http://www.linuxcomputersystems.com/

Pentium Compiler Group
A freely available, highly optimizing compiler based on GNU cc (GCC). Precompiled packages available for Linux, DJGPP, OS/2, FreeBSD, Solaris...
http://www.goof.com/pcg/

Pentium Farm
At the University of Mannheim. Configuration details.
http://suparum.rz.uni-mannheim.de/Linux/farm.html

Hercules
An open-source emulator of S/370 and ESA/390 which runs under Linux on a Pentium PC.
http://www.conmicro.cx/hercules/

Carrera Computers
Pentium-based Beowulf clusters. Product specs.
http://www.carrera.com/

Global American, Inc.
Global American, Inc. supplies and services Industrial Computer Systems and Components
http://www.globalamericaninc.com/

ZUSE Parallel Pentium-Pro Cluster
At the University of Koblenz-Landau. Configuration diagram.
http://www.uni-koblenz.de/~evol/zuse/zuse.html

Microway
Microway - Designers and Manufacturers of HPC Solutions Since 1982
http://www.microway.com/

Stampede Linux
Distribution with speed enhancements for Pentium level computers, ships with KDE.
http://www.stampede.org/

Stampede Linux
Distribution optimized for Pentium-class systems, for new and experienced users.
http://www.stampede.org/