I am running a default install on Kubuntu Edgy on a Latitude D600. The only things that isn't working yet is the Broadcom wifi - I haven't even tried but I know that it will work. Also, I have turned the modem off as I have no need for it, so I have no idea if it is working. Suspend and all of the Fn keys worked out of the box. I a using my new Latitude right now
This is NOT an advert for Kubuntu : just to say that everything will work using Linux. Good luck!!