Aside from the suggestions Dave made, there is no purposeful saving of older
workbook versions built into Excel. However, I use a free utility called
AutoSafe (I've disabled Excel's own autosave feature), available from
http://jkp-ads.com, which regularly saves a backup in a directory you
choose. When it saves a new backup, the old one is in the recycle bin. I
allow typically a few days of backups to accumulate in the recycle bin, so I
can retrieve something critical.
- Jon