Cisco VPN client does not go through Windows 2003 router

Hi,

I recently switch from using a Linksys router to a Windows 2003 server
configured as a router. Everything seems to be working as expected. I
am also able to use standard Microsoft VPN client to connect to the
outside world.

The only problem that I am running into is that Cisco VPN client does
not work. I can connect to the host and register my machine. However,
I cannot ping to any machine on the host system. This setup used to
work flawlessly with the Linksys router.

Does anyone have any idea on what could be going on? I even tried to
turn Internet Connection Firewall (ICF) off on the WAN connection. But
this did not help.

On the Windows 2003 system, all I had to do was to turn on "Allow
Internet Sharing" on the WAN network card. Very simple. I didn't even
have to install "Routing and Remote Access" Windows component. Now I
am wondering if this is the problem.

Thank you in advance for your help.

Pradeep