Ok people I need your

Ok people I need your help. I'm a bit of a pop princess with likings for most other stuff too. However my R&B knowledge is somewhat lacking!!

And... I'm DJing an event next week which is Chart & RnB (not much cheese) so I need help!
I don't know the scene very well and don't know what goes down 'big stylee', other than stuff like Beyonce, Misteeq, 50 cent etc...

So let me know any fab R&B tracks that I can fill 4 hours with!

Thanks