[squid-users] Can Squid Acc. accelerate WindowsUpdate ?!

I need accelerating WindowsUpdate procedure in my network, where I'm
actually using Squid 2.5 to go out to the public network; Windows clients
must be often updating because there is no remote system to admin.
There are acl to permit navigation to some users and in this case their
browser have this proxy to reference, while other users have no
configuration.
I thought to use another machine acting as squid accelerator next to
original Squid.
I configured Squid accel. like this:

http_port 80

httpd_accel_host virtual
httpd_accel_port 0
httpd_accel_with_proxy off
httpd_accel_single_host off
redirect_program /usr/local/bin/map --> script

Squid accelerator has no parent cache.
This Squid accelerator has two network interface cards: one on public
network and the other on my lan. I configured 3 virtual IP address on public
network NIC, because I used a Perl script to point to three domains:

192.168.0.1 v4.windowsupdate.microsoft.com
192.168.0.2 www.windowsupdate.com
192.168.0.3 www.microsoft.com

I set my IE 6 browser with no proxy and and no detect automatically
configuration.
I run squid accel. and typing in browser url http://192.168.0.2 Windows
update likes starting to terminate abnormally. I can't understand how to
solve problem.
I'd like accelerating users to download patches, service packs at high
speed.... even if someone have no proxy set in I.E.
In this way I can reach WindowsUpdate from any point in my lan regardless
Internet Explorer settings.

Best regards

Sampei