iPhone 4G iOS 5.1 iTunes Has Multiple Backups i Hope. How i Access Them

Yesterday, my iPhone 4G, iOS 5.1, spontaneously went into restore mode, and Sprint Tech Support told me the only thing I could do was restore.  The iTunes installation I used to restore was two months old, so I lost many of my apps, photos, contacts, and calls. Trying to recover them, I opened iTunes on another notebook I had last used about two weeks before.  The first thing iTunes told me to do is synch my iPhone with iTunes.  Did that, and now it iTurns out that the only backup that appears to be available is the one I just created.  Not exactly what I need.  Three questions:

1.  Does iTunes not keep multiple backups, like BlackBerry does? 

2.  If it does not, what the @#$%^&* were they thinking? 

3.  If it does, how do I access the last backup before the Crash of Quatro de Mayo?