Is there a command line tool for Windows XP to display system resources, like available memory usage, cpu, diskspace etc... Small and requires a non-install.
The built-in command 'tasklist' will give some information and has some useful command switches. Another option would be to run 'perfmon.msc' from the command line. This will open a window with useful information.
Another alternative, keeping it entirely command line based is PsTools from Sysinternals. This provides access to a number of very powerful utilities.