Linux on old computers

Quick answer: Debian, Slackware, or perhaps BasicLinux (current version), or an older version of RedHat, Mandrake, or SuSE. Justification: RedHat, Mandrake, SuSE, Caldera, and TurboLinux are optimized/suitable for hardware current at the date of their release. They may be difficult or impossible to install on older machines mostly due to the memory contraints and speed. Debian and Slackware are suitable for most older hardware as well. At the begining of installation on older hardware, watch for the initial prompt to start the installation in the "text mode".