First, I want to thank the folks at Sagebrush Consultants for sharing
the information on digital USGS maps.  It was very helpful.
 
I would, however, correct one thing.  To my knowledge, there is no
reason you could not use raster images in a GIS application.  The ease with
which it can be done depends upon your software and hardware capabilities.
The utility of doing so depends on what sort of questions you are
asking.  They (being the techno-wizards) are rapidly improving raster-to-
vector conversion programs which may make this a reasonable option by the
time USGS maps are available in your area.
 
Shannon Dawdy
University of New Orleans