dell precision m50 _very_ slow paging/swapping

Although Dell doesn't consider the precision M50 a laptop (it's a
"portable workstation"), this list
looks like a good place to start :-)

I'm having a big problem with a brand-new M50.  The symptoms persist
whether I try Redhat 7.3
or 8.0.

Generally, everything is fine, right up to the time the machine starts
paging out to disk.  Then, the
system essentially grinds to a halt.

The paging activity eventually gets done, and, once things are running
in RAM, the machine flies.

However, I've seen starting mozilla take ~45 seconds, and starting vi
take 15!!!

This machine:

    1.8Ghz Pentium 4 Pro Mobile CPU
    256MB RAM
    40 GB hard drive (userland benchmarks look good - 16-18 MB/sec
transfer rates)
    nVidia Quadro 4 GoGl video
    PIIX4 EIDE chipset
    i810 compatible sound
    Latest BIOS upgrade from Dell (A07)

I see the same result with redhat 7.3 and 8.0.

I've even disabled the PIIX support in the kernel, on the theory that
something in the IDE
subsystem was responsible - no change, except (as expected) user mode
disk IO slowed down
somewhat.

I freely admit I'm confused.

Dell support is:
    1 - extremely frustrating
    2 - totally useless

And I don't even want to talk about Redhat.

Can anyone point me at a theory, even??