I too had this problem...but...I was able to find help on the technet forums
and was able to get the system to run (and in only a few minutes). See the
following threads:
http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=472019&SiteID=17&PageID=1
First, be sure you have the newest version of the Vista Upgrade
Advisor...the version I am using now is v. 1 (downloaded just today)....be
sure you have completely uninstalled any earlier versions.
Secondly, be sure before you run the advisor that the VUA files in the temp
directory (C:/documents and settings/<username>/localsettings/temp) are
deleted.
When the Advisor runs correctly, there should be at least four files there:
VUA_Bucketizer_DELLLAPTOPCA.xml
VUA_Collector_DELLLAPTOPCA.xml
VUA_QueryAppBlock_DELLLAPTOPCA.xml
VUA_WinSat_DELLLAPTOPCA.xml
When it did not run correctly, one 3 files were present. After deleting
these files and rerunning the VUA, it ran perfectly in only a few mins.
DELLLAPTOPCA in my case refers to the name of MY machine...yours will be
different.
Hope this works!