determine what user is logged in remotely (command line)

Windows XP:
I’d like to perform an audit on the office by pinging an IP address (known) and resolving it to a hostname (unknown). I am using ping -a xxx.xxx.xxx.xxx

Is there another command or parameter I can use that will tell me what user is logged in to a particular hostname/IP address?

I have a feeling the %username% variable might be involved.

Any ideas?