thenelson,
There is no difference related to this question in client and server OS. Authentication is done the same way.
MarkRod,
I assume it is an issue with the GUI. As long as noone is logged in, no GUI can be used, and that might stop Access (never tried it though). If this is the case, you can try to use psexec of the famous SysInternals suite (
www.sysinternals.com, free; now owned by Microsoft). psexec -x can start a program on the local WinLogon screen. However, this only works as LocalSystem, so you still might have a permission issue.