Linux users are not an easy bunch to profile or to count. Many Linux users download the operating system for free and never perform any kind of systems registration to enumerate their hardware.
That's where Smolt may be able to help fill the gap. Smolt is an open source hardware profiling technology that is already being used by Red Hat's Fedora and is set for inclusion in the upcoming Novell OpenSUSE 11.1 release. Ubuntu is currently considering Smolt as well.