itunes - automatic backups issue

I have an iphone 4 (ios 5.0.1) and itunes (10.5.2.11) installed on Windows 7 PC.

From researching it appears itunes retains only one backup per apple device. If this is true, my problem is this: itunes is automatically creating a backup each time I attach my phone to my PC. Ordinarlily this would be a good thing. However, when one has a non-functioning iphone, the last thing one wants is for the last (possibly good) backup to be overwritten by itunes doing an automatic backup.

How can I stop or control itunes such that I can manually perform the backup when I want to, rather that it doing it automatically? I can't find any options to disable the automatic backup. (Note: I realize I could keep backing up the itunes backup directory on my PC manually but I do not want to create work for myself).