How odd...

In order to get different map images for the same location to line up, both maps need (1) the same projection and (2) the same datum.

I know that MSRMaps/Terraserver and Google use different projections and I have taken care of that in the code.

But they both claim to essentially use the same datum (WGS84 and NAD83).

Here's a link to a random spot in north CA. The center of the map is a section corner. The two topo maps are almost perfectly aligned.
http://www.mappingsupport.com/p/gmap4.php?ll=41.524239,-122.709137&t=t3&z=16

I have checked a number of spots in several midwest states and they are also aligned correctly.

I'm going to email the staff working on MicrosoftMSRMaps/Terraserver and see if they can shed light.