If you took the most recent Linkin Park song and played it next to their earlier works, you'll notice a definite difference in sound. People change as they get older, and the same can be said for Linkin Park. 2007 would be around the time this shift was made, and the song to send off the old Linkin Park was "What I've Done", their first single off their studio album "Minutes to Midnight" .
The song was also used in Michael Bay's movie Transformers!