查询Windows是否由UpgradeCode安装了应用程序

I have been trying to query Window (XP and Vista) to see if any version of one of our software packages is installed with the UpgradeCode (In this case the UpgradeCode is the only static GUID from version to version). I have tried to do this with WMI and the WindowInstaller.Installer object but have not been successful. I have to write this query from C#. Thanks for any assistance or direction you can provide. I have been trying to query Window (XP and Vist