Our low-cost cluster of 32 Athlon PCs (see February 2001 highlight) has been in constant use by local users, providing a substantial and very cost-effective boost to our group's large-scale simulation capabilities. To satisfy demand, we have added two additional 32-processor clusters with higher performance at an even lower cost. On this platform, the freely available simulation code NAMD can complete a 1 nanosecond simulation of the 60,000 atom aquaporin-1 water channel with full electrostatics and constant pressure in a single week. We have given three tutorials, both filled to capacity, introducing participants to cluster hardware and software with the aid of a hands-on session assembling and installing four-processor clusters (see photo).