[kinook]

For setup projects, the VS.NET Get Version action retrieves the project's ProductVersion value. This is typically a three-segment version (i.e., 1.0.2), but the action simply retrieves the value as-is from the .vdproj file.
http://www.visualbuild.com/Manual/vs_netprojver.htm

To change the value of the macro set by the action, you can use code like (VBScript)

Set m = vbld_TempMacro("VSNET_PROJ_VER")
' given a macro value like 1.1, convert to 1.0.0.1
m.Value = Left(m.Value, 1) + ".0.0" + Mid(m.Value, 2)

http://www.visualbuild.com/Manual/systemscripts.htm
http://www.visualbuild.com/Manual/objectmodel.htm