Transfac is probably what you're looking for. However, it's a proprietary product

http://genexplain.com/transfac/

They do a free trial which may fulfil your immediate needs.

Dear Christian & Priyanka,

Thank you very much for your advice. 

BW, Simon

Dear Dr Waddington, I can also recommend Transfac.  Or get in touch to see if we can help out!  Alternatively,  try the newly developed technique of SMiLE Seq to discover what transcription factors are bound.  Good luck!

Dear

I purpose you helpfull links: 

jaspar.cgb.ki.se/

http://genome.ufl.edu/mapper/run/?init=db

http://tfbs.genereg.net/

Regards