if by "sign on" you mean "log on", then there is the "Deny logon locally"
option in the Local Security Policy.
There is also the "Logon to" option in the user account properties. Here you
can specify the computers (clients or servers) that the user can log on to
and any system that is not included here will not allow the person to logon.
--
Sincerely,
Dèjì Akómöláfé, MCSE MCSA MCP+I www.akomolafe.com www.iyaburo.com
Do you now realize that Today is the Tomorrow you were worried about
Yesterday? -anon