user agent string to block Windows XP machine on an Ironport

[flyerhawk]

Does anyone know the best RegEx String to use to block Windows XP machines from being able to go to the Internet via an Ironport user agent filter?

[Jernej Vodopivec]

This should do it:

Mozilla/.*Windows NT 5\.1.*rv:.*like Gecko
Mozilla/.*MSIE.*Windows NT 5\.1