Kernels is a project mainly written in PHP, it's free.
Collections of kernels used in the project
Kernels for different hardware, in Archlinux [1] package format.
For an AMD Athlon XP 2000+ system includes: Xenomai, Analogy, Comedi
For Celeron M laptop includes: Xenomai, Analogy
[1] http://archlinux.org