Where is my Iphone's backup stored?

I was just trying to sync some songs to my iphone, but it started to backup. During that my computer ran out of space (because of the backup) and now the backup wasn't finished (so it didn't appear on the preferences) and I have no idea where it is! And my computer is out of space. What do I do? I have no idea where to find the unfinished backup…

Btw I have an Iphone 4s with ios 6.0.1 and my computer is windows vista if that helps…

ICLOUD