At the time I answered this question back in 1997, these missions had not as yet arrived at Mars. Since then, of course, they not only arrived, but returned some of the most dramatic images of the Red Planet ever seen in decades.
To see the results, visit the Mars Pathfinder web site at JPL and look at some of the excellent images, many in 3-d, taken at the 'Sagan Station' on the surface of the planet.
For the Mars Global Surveyor, JPL also has a web site with images from this mission, including high resolution views of the Face of Mars!
Following the disasterous loss of the Mars Polar Lander in 1999, NASA is completely reevaluating its surface rover mission Mars Surveyor 2003 so we will have to wait and see what this mission will have to mutate into to satisfy the concerns of NASA over mission reliability.
Previous errors which caused the loss of the Mars Orbiter and the Mars Polar Lander have conclusively been tied to silly software errors. In the first case, it was a contractor who used English rather than Metric units to determine the orbit insertion parameters. In the later case, a missing line of code caused the descent engine to shut of as the landing legs were being deployed.
Copyright 1997 Dr. Sten Odenwald
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