How i can configure a proxy server on a windows installation?

I currently use Exchange running on Windows 2003 behind an internet facing Ubuntu server.
To use squid to proxy RPC-HTTP and OWA connections to Exchange I use the following lines in /etc/squid/squid.conf:

<pub_domain> = The domain you wish to forward to the exchange server (eg: exchange.mycompany.com)
<int_ip> = mail server ip (eg: 192.168.1.2)
<ACL> = A made up name for the acl (eg: EXCHANGE)

cache_peer <int_ip> parent 80 0 no-query originserver login=PASS front-end-https=on name=<pub_domain>
acl <ACL> dstdomain <pub_domain>
cache_peer_access <pub_domain> allow <ACL>
never_direct allow <ACL>
http_access allow <ACL>
miss_access allow <ACL>

This will forward all queries to exchange.mycompany.com to your Exchange server which will need RPC-HTTP enabled as well as OWA and answers those requests on port 80.
I am using the squid process to answer on port 443 to secure the connections with a line like the following in squid.conf:
https_port 443 cert=/etc/apache2/ssl/mail_server.pem key=/etc/apache2/ssl/mail_privatekey.pem defaultsite=<pub_domain> vhost

This gives me https access to email from outside the company with:
Evolution on Linux via OWA
Outlook in Windows via RPC-HTTP
Windows Mobile push mail support via OWA

The configuration of the Exchange server is reasonably straight forward, but not completely obvious. I found a tutorial via google for it.

Side notes:
I force all mail clients to access Exchange via squid. This way they work inside or outside the company without reconfiguring. Squid does not pass NTLM auth for Outlook, and thus requires Basic Authentication for RPC-HTTP which requires the user type their password to connect.
I am having trouble getting Evolution to connect via https with a CAcert issued certificate on the server. Http if fine though (secured via a ssh tunnel at the mo).
We also use squid for proxying our public website without a problem.