Thanks for the link. I will check with the IT department where the server is hosted to see about some of these details. However, I don't think there is any blockage at their end as I use this tunnel all the time with my old Compaq NC6000 running exactly the same version of Windows XP, so the problem is either on my Mac or because Parallels is blocking the information.
I never actually see the "Checking for Banner Text" window when I run the VPN Client on my Mac, I just get a timeout error (I think from the server) that says the user did not acknowledge the Banner Text.
I'll give this some more thought and effort tomorrow. Thanks for your help today.