Its even cheaper if you go here:
Overclockers.co.uk - 88 quid
Bargainous i say!
Saying that, i've just snaffled some of the 4-4-4-12 PC8000 Cellshock sticks off ebay for 87 quid, so the bargains are out there if you shop around
The PC8000's have micron D9GKX chips, which are apparently better than those on the 6400's, so should overclock even harder so i'm told