Well, it's been an eventful few days. What I've done is to clean
install 10.04, then I allowed all the updates to install. I ran with
the nouveau video driver for a day but got system wide freezing. Then I
installed the Nvidia driver and the freezing got worse.

Then I ran across this thread in the Ubuntu forums, dealing with the
same or similar problems.
http://ubuntuforums.org/showthread.php?t=1478787 Seems that I am not
alone as there are several hundred posts in it. Lots of people are
blaming the kernel 2.6.32-35 generic which is what 10.04 updates to.

So I downloaded and installed 10.10 64 bit, which uses 2.6.35 something,
but had the freezing problem right away. Somewhere along the line I
learned how to install /home in a separate partition, so at least I
don't have to re-install all my stuff every time.

Lastly, I clean installed 10.04 again and allowed updates to install
EXCEPT for anything to do with the kernel or kernel headers. I've since
installed the Nvidia driver and the restricted extras package. Has been
running this way since last night - no freeze ups.

Think I will run this way for now, at least until a kernel newer than
2.6.32-25 is released.