If you are going to use LWP to get files from that server, you can get information back from the HTTP header.

Look into the HTTP::Response module for your user agent. From there call my $hdrs = $response->headers(); to get the HTTP::Headers object from the server.

From there you'll be looking to use

$hdrs->content_type; # this returns a lowercase string
[download]

Hope this will get you on your way. Good luck with the spider.

    --jb