Are your PCs under a single domain, or do all have separate and different user accounts and passwords? If they're under a single domain, you can do the checking through a network script loaded on logon. You'll probably want to ask whoever's the sysadmin to do the scripting though.

http://www.activexperts.com/activmonitor/w...gement/scripts/
http://www.windowsnetworking.com/articles_...ipts-Part9.html
These 2 might help.