i use mandrake 9.1 on a dell inspiron 8200. i got almost everything working within the first few days, which is saying a lot, because i was doing it without a friend helping me and without any prior experience. i still don't have power saving features like standby working, however. i've been doing some looking on this site and elsewhere, but i'm a little hesitant to try anything drastic because i read of a couple people having troubles. however, the fans worked automatically, so i just let it stay on most of the time.
as for the dell truemobile, i have one (forgetting the model # right now and can't find the box). it worked right out of the box on the first boot. as long as the model you want is prism2 based it should be fine. there's a lot of threads on this site about notebook cards.
hope that helps.