5 is a strange number of wires to have - are there 2 earth wires twisted together in one bit of green and yellow sleeving?
Remember to switch the power off at the consumer unit!
I'm assuming (can't be certain without actually looking at it) what you'll need to do is put:
the two red wires together in a bit of terminal block, one of the black wires should have a red marker on it - this goes in the live terminal of the fitting.
The other black wire goes in the neutral of the fitting.
The earth wires go in the earth terminal of the fitting.
Adam
January 2009