Microsoft VPN on Cisxo PIX Firewall

We would like to switch our VPN software from Cisco to the Microsoft VPN
software which is part of Windows XP. I have been in contact with Cisco to
determine what I need to add to the Cisco PIX 515e firewall to allow this
access, but I have not received any substantial response from them.

Can anyone tell me what additional commands I need to add to the firewall to
get Microsoft VPN to work?