That's my thinking about the power. Generally, a 350W PSU isn't enough for a water cooled setup - pretty much because if you are running when then it is most likely you are also running a high performance setup which therefore needs a lot more power. I upgraded to the GlobalWin SAF 520W for this purpose.
BTW, more news on my setup. Gavin took the case and rad/shroud away to cut everything out and realised that where we were gonna put it will require more cutting from the 5.25" bay (it's inside at the top and hard to see) than would be good for the case. So he's checked out the price of aluminium from his supplier and it'll be about £20 - £30 for enough to make a box. So I'm gonna make up a design and then he'll do that for me.
I'll draw something up later and post it here so you guys can pass opinions