The user agent string issue arises when you are behind a web proxy (e.g. trying to use CPAN from work), and the outbound proxy in the corporate firewall cares about the user agent string. You're expected to use a recent version of NS or IE (or Mozilla). There is a separate allowed UAS reserveed for programs fetching stuff from the web, but it's not the one the LWP gives out.

I agree that the mirrors typically don't care.

--Bob Niederman, http://bob-n.com