Windows 2003 Server

i just installed Window server 2003 on my network with 2 XP PCs. I am unable to ping the Server 2003 PC from my XP clients. However, I can ping the XP PCs from the Server. I ahve turn off Windows Firewall on all PCs to make sure that wasn’t the case. Can anyoone help me figure out why I cannot ping my Server. I can ping my Router!

Brgds
Julie