Is there an equivalent in Windows for the
w command in Linux/Unix?
depending on what you are looking for
query session, or
query process will provide similar functionality. Tasklist /v is also useful. Typical windows workstations are single purpose. Servers usually have few actual users on them (with the exception of terminal servers) so I haven't seen a real need for a "w" type command.
Yet another way would be to use
WMIC list process brief However to get owner info you would have to call getowner for a process you are interested in.
for detailed process info you can use
wmic /output:wmic.html process list full /format:hform
and view the wmic.html file in your browser