Linux on Laptops, until I learned of the FreeBSD Laptop Compatibility List. This site even had an entry for my Thinkpad a20p. There's an article at Freebsd.org and another database of information also available.
I've had various versions of FreeBSD running on this laptop since I tried installing FreeBSD 4.1.1. I plan to install FreeBSD 5.2 REL once issues in the todo list are solved.