Re: another stupid question

GENERIC is more likely to be ok with 4.0 than it was with say 1.6, so
I'd advise at least trying it.

I'm not sure about the sources.  What I'd do is pull from anonymous cvs
with one of the following tags (e.g., use "-r netbsd-4" on your checkout):

  netbsd-4-0-RELEASE	the release, exactly
  netbsd-4-0            security fix branch for 4.0
  netbsd-4              stable branch for 4 (4.1 will be from this some day)

It's perfectly ok to have a slightly newer kernel from the netbsd-4 or
netbsd-4-0 branches than your userland.  The branch rules are more or
less bug and security fixes only, no structural changes, no ABI/API
changes.

I use tags like netbsd-4 on production machines, and update both
userland and kernel from source.  (While technically it's required to
have a newer kernel than user, I find that along a stable branch I can
install both and reboot with no trouble.  When jumping branches I always
install the kernel and reboot and then install userland.)

So I would suggest that you build a kernel from the netbsd-4 branch.