If your desktop area is 640X480, you 
will need to choose the Custom Installation
and only install the 640X480 Modules.

The Typical install will install all 
6 Modules at 800X600. If you do not wish 
to install all the Modules, choose Custom 
and select only the ones you wish.

The Compact install will install Module 1
for a desktop size of 800X600