The link that jointgib posted is Damian Marley’s Just Ain’t The Same, which is a shameless ripoff of the classic Dr Dre track The Watcher from the album Chronic 2001, to which ElizaD provided the lyrics.
http://www.youtube.com/watch?v=H8ezWOEiLF8
Dr Dre himself is not much of a writer and his extensive use of ghostwriters is an open secret, as they say. The Watcher was largely written by Snoop Dogg and Eminem.
Dre is however a great producer and has a knack of digging up and making good use of samples. He butchered Led Zeppelin’s Kashmir into an unrecognisable form for Fight Music by D12. Another track from Chronic 2001, called What’s the Difference has as its base a slowed down version of the intro to “Parce que tu crois” by Charles Aznavour.