> What I want to know is what kinds of problems I might experience when I
> move to a 'free' kernel? Are these problems easily discoverable when I
> switch? I'm most concerned about two possibilities - my system becomes
> inoperable due to some dependency on binary firmware; or the absence of
> the firmware introduces some subtle change that may cause headaches
> without providing a clear indication that the lack of firmware is the
> source of the problem.
By "free" are you meaning a kernel you have compiled for yourself from
source? In that case, you would include any needed modules and add
the firmware for your hardware.
You don't mean a pre-compiled kernel from some other distro do you, there
might/could be important differences with that and which could potentially
cause you problems.
> ps. I'm running Squeeze on a Thinkpad R60, but I'm interested in the
> general case as well.
People running testing are supposed to be more advanced than needing to
ask this question. No offence meant but I think that is especially true
this soon after a stable release, when "testing" isn't close to a release