I've just installed NetBSD/i386 1.6 on a said Dell laptop and well,
it's pretty sucky. 

NetBSD runs well enough of course, and the laptop seems to run well
enough, it just seems to be the combination of the two. 

Most of the problem seems to be BIOS interaction (I'm guessing). The
main symptom is that the screen will go completely blank and the
keyboard becomes unresponsive. I have to power cycle the laptop at
this point. I think it's the APM BIOS that causes this because it only
happens when I'm not looking at the laptop. I've switched power
management off in the BIOS for the AC supply (which I'm using) and it
doesn't seem to help. 

Also any time I press any of the magic key combinations involving the
Fn key (accidently or otherwise), the machine stops working with no
indication of any problem other than the lack of responsiveness.

I also have the X problems mentioned by Ian Harding, but I haven't had
a chance to follow David Brownlee's MTRR suggestion. Something about
having to use the laptop for work during the day, or some such
nonsense.

Does anyone have any success stories with the C640? Perhaps I need to
rebuild with the apm driver active. 

TIA
Lloyd Parkes