[^netscape\.com|^microsoft\.com]

##</code><code>##

(?!netscape.com)(?!microsoft.com)

##</code><code>##

http://(?:.*?)

##</code><code>##

$page =~ m%<noframes>.*?<a href *= *"(http://(?!netscape.com)(?!microsoft.com)(?:\w+\.)(?!netscape.com)(?!microsoft.com)[^"]+)"%is;