Locating my backup files on iTunes

Hi all, I have recently upgraded my iPad 1 to OS 5.0.1. I have a PC running Vista where iTunes is installed. In the process I took a back up before proceeding. The upgrade proved problematic but I got thorugh it after several attempts however I use an App called iThoughts (mindmapping tool) a lot for work and all of the files are now gone. I have looked on the iThoughts website which gives instructions on how to extract the specific mindmap files if you can locate the backup file on iTunes. However, I don’t appear to have the standard folder structure as indicated on many websites i.e. \Users\(username)\AppData\Roaming\Apple Computer\MobileSync\Backup\ On mine it is \Users\(username)\Roaming and that’s it! So where could my backup file be? I have tried to find the file extension online so I can do a seach on the hard drive but can’t seem to find that information either… Can anyone help me locate the backup file so I can get my iThoughts files back? Brian