I am currently using Ubuntu on a Compaq Presario V2000 laptop. I really like it, but it is one of the most limited of the linux distros in terms of learning. The newest ubuntu release, 7.04 , will be released April 19th. The beta is currently out, but I would recommend waiting until it is fully released. It is supposed to be more hardware-friendly for laptops and networking.
I would also reccomend using GNOME over KDE, as I found KDE to be a huge memory-hog on my laptop.
daedalus