I did a full backup of my machine, then reinitialized the hard drive and installed Snow Leopard. Then I upgraded to Mavericks. When I did the data migration from Time Machine it told me "this user needs work before migrating", it is the only user set up.
I went ahead and did a migration, but none of my pesronal settings such as very important bookmarks in Firefox.
Mac mini, OS X Mavericks (10.9)