OK, so I know that I can recover the most recent iPhone backup and that I can restore it by using iTunes and that if I really want I can find a piece of software to open up the backup and recover information manually.
But..... is there any way of going back to a previous backup, say a week before the one displayed in itunes. I understand that each backup probably gets over written by the new one but I still need to know if there is a way to go back one step?

The reason for this is that my PC decided to corrupt the pst file in Outlook 2007 therefore damaging the contacts on my iphone, my iPhone then very cleverly did a backup before I had realised that all the contacts had been screwed up, I now can't go backwards and I'm stuck with a lot of incorrect contact info. If I could go back a few days to before the pst was damaged then I'd be saved.
I run a MacBook Pro but this problem is on a PC.
Thanks in advance.