Microsoft Firewall client and Cisco VPN Client

Hi netters, I'm experiencing the following when trying to use Cisco VPN Client from the internal network running ISA Server:

- in order for the VPN Client to work and connected to the outside Cisco VPN Server, I have to remove Microsoft Firewall Client, which we use it to connect to the ISA server then to the internet.

My question is:

1)Does those two - the Cisco VPN CLient and the Microsoft Firewall Client - are not compatible

2)In order to get Cisco VPN to work, SecureNAT requires an WinXP workstation inside the ISA Firewall to have a static IP Address(is it?), open specific UDP ports used by Cisco VPN in the ISA Server to SendReceive.

3) Is there better solution, therefore I do not have to do this hassle to get a secure VPN Connection to the outside.

Thanks and your help is greatly appreciated.