iPhone 5 - Backup Files

My iPhone 3gs with 32 gig memory became unresponsive. I bought and iPhone 5 with 16GB memory. I went to setup iPhone 5 but did not get everything. Only 14GB was used on 3GS. I have my backup on my Windows XP based netbook with iTunes used for backup, etc. Though I have done numerous backups over the years, only one shows as available. Does iTunes overwrite the last backup each time a backup is done?

If so, what files can I move to a different location so they are not overwritten?

via iLounge Forums http://forums.ilounge.com/iphone/278336-iphone-5-backup-files.html