Just to add a "me too" to the ranks of Linux supporters out there --
The Netscape Open Directory Project (formerly "NewHoo", prior to being
acquired by Netscape) runs on Red Hat Linux.
Our servers are not the average Fry's clone -- we use 2 CPU P450's custom
built from Telenet Systems in San Jose. These systems have six fans,
two hot-swappable power supplies, and come in a rackmount enclosure
weighing 80 pounds. Currently we have two of these systems, one for
editing and to serve the directory on http://directory.mozilla.org, and the other to handle search cgi's.
The Open Directory Project is using an Open Content development model
to build the world's biggest web directory. The resulting directory
database is being used on Netscape.com, and is freely available to others
on the web. See http://directory.mozilla.org/about.html for a link to
the download page.