Win2k3 – logon / logoff events

Dear ALl

We are having win2k3 server acting as domain controller for our office. All our workstations are windows XP, joined in the domain.

My problem is i am not getting logon / logoff
events of my workstations and server logon & logoff events in event viewer of domain controller. How do I resolve this.Kindly help

Regards
Sakthi