1 GHz eMac, 256 megs, 60 gig, did clean install of OS X using the
discs that came with the computer. Now the screen is about 6 inches
across (and it's a 17 inch monitor). I reinstalled it two more times
with the same result. This was posted on the apple.com support page:

eMac (ATI Graphics) - Distorted or Shrunken Video
If you install an earlier version of system software
on your eMac (ATI Graphics) than the version it shipped with, it can
cause the display image to appear very small or to distort.
Symptom

The display image is smaller than normal or distorted.

The volume, mute, and eject keys of your Apple Pro Keyboard (2003) do
not operate.

Products affected
eMac (ATI Graphics)
Mac OS 9
Mac OS X

Solution

Use the software discs that came with the eMac (ATI Graphics) to
reinstall the system software. Consult the eMac User's Guide that came
with your computer for more information.

Important: Despite the fact that your system software may have the
same version number, different components may be installed. This can
be true for both Mac OS 9 and Mac OS X. Because of this, you should be
sure to use the original software discs that came with your computer
when reinstalling software


But I'm using the original discs, so now what???

thanks for any help!