we use the log file that's automatically generated by Target Designer when
you build.
Also we store the different versions of this log file on VSS which we can
then use to compare versions of your build.
Note: you'll need VSS 2005 or later as earlier versions won't do a diff on
unicode text files. Alternatively open the log file in notepad and save it
as a utf-8 text file then you can use older vss versions.