Screen resolution loop [help!]

[David Armour]

On my up-to-date Hardy machine (workhorse3), the LCD displays 1280 x 1024.
Workhorse5, however, with the very same LCD(!) sets up at 640 x 480, and resists
all efforts (mine, at least) to painlessly switch to higher resolutions. (See
below.) A 640 x 480 resolution, admittedly, makes the numbers big & easy to
read, but also unfortunately all-too-often sacrifices key bits (e.g.
close/resize, scroll bars) to the nether-world off-screen.  

Hoping to circumvent the hundreds of usual post-release up-dates, and perhaps
gain the benefits of a new(-er), improved! Ubuntu, I kludgely downloaded
'Intrepid-Alpha6' and found 304 (!) up-dates waiting in the wings ... 

Worse, once the system was supposedly 'up-to-date', and I had picked the
'recommended' Nvidia driver from the System>Hardware Drivers> drop-down, and
pressed Crtl-Alt-Backspace "... to 'restart' X server", I got:
      [screen goes black, with blinking cursor in top left corner]
	[requires cold re-boot]
       restarting Ubuntu displays the loading 'thermometer', then a CLI screen
with a log-in prompt too brief to complete, before returning to:		[screen goes
black / requires cold re-boot] 

...which is where I had come in with the Hardy install.

Workhorse5 also works fine at 1280x1024 with puppy-linux, but for now, I'm
mostly interested in getting out of this Ubuntu log-in loop. Any ideas?