With Worksets and Central/Local Files there are two options to restore from a Backup; Save As and Roll Back. I'm focusing on the first. To use it you have to open the backups folder of the project you are working on via the File menu > Backups...
Now you select the previous version and choose Save As: (yeah this image only has one previous version...I was lazy)
When you use Save As you are NOT creating a NEW Central File as might be expected. You are actually creating a NEW LOCAL FILE according to the conditions of the project at the time of that Saved Back Up. This means using Save to Central is NOT a good idea!
In order to protect the integrity of the current project file you should immediately use the File menu > Save As, provide a new name and folder location, Click Options and check the "Make this a Central file after Save" option, Click OK, Click OK.
Regarding 2010 there are some subtle changes. First there is a new location for the newly renamed "Restore Backup" feature.
There is a slightly different File Save Options dialog too:
The result of choosing the Specify option means that when a user makes a Local File the Specify Worksets dialog will appear, which enhances the new procedure available for making local files. Whichever selection is made is the one that Local file each user creates will exhibit.
Oh and Save to Central (STC) is now called Synchronize with Central (SWC).