is that all that needs backing up? I'm sure I recall someone mentioning once that there were some other files in other locations that needed to be copied as well.
That what you said it`n not enough to run old save game after pc format. You must copy the "xlive" folder from C:\Users\<user name>\AppData\Local\Microsoft. Thats two folders are all save for F1 2011. First is Save Game, but second is GFWL account and you need this folders together.
Sorry for my very, very bat english but I`m from Poland and I don`t speak english very well