I was origionaly using windows 2000 Prof. inbuilt VPN Client software to
connect via the Internet to a Cisco PIX 506e (acting as the VPN Server)
using PPTP - which works fine. Some of the client PC's requiring
connection to the PIX are protected from the Internet via a Border Manager
firewall and can't get connected (hangs on the verifying username &
password stage), we have learnt that this problem is caused by BM not
passing GRE thru the firewall.

My questions are :-

1). Is this true, or are their any workarounds ?
2). Will Microsoft L2TP/IPSec VPN Client pass through Border Manager ?
3). Is their any other VPN Client software that will pass through Border
Manager ? i.e. Cisco VPN Client 3.6