WOOOOH! Hang on though, if you are doing a format / reinstall then you also need to back up more!
What Ned did is fine for simply going back in time on your exisiting game, but on a fresh install you need to consider your GFWL live data, plus the fact there will not be an existing game profile after a vanilla install.
Yes you need to back up the F1 save game files in My Documents as described, and GFWL stuff, but on a clean install, you must start a new game, and then exit out. Then, from the new save game folders created, delete the new files and copy in you old backup files. DONT REPLACE the entire NEW folder, just copy your OLD FILES, into the NEW folder.
Obviously you need to do a similar replacement for the GFWL files. Im not sure off the top of my head where that stuff is, but you defo need it. Sorry I cant pinpoint it all for you.
Search the forum as its been covered before.
P.