You may recall last week's attempt at reinstalling my watercooling went a bit wrong. Yesterday I had another go with a simpler loop and things have gone a lot better.
After a couple of hours leak testing outside the case I put the loop into the PC, mounting the 120mm Black Ice Extreme radiator and the DangerDen RBX waterblock, with the pump hanging around in there somewhere too.
The system booted and didn't BSOD, so I knew I was on a winner, but temperatures were only a few degrees lower than the stock AMD cooler. I wiggled the block slightly and tightened it a little more and knocked a further 7-8 degrees off the CPU temperature.
Right now the CPU is reading 30, hitting about 36 under load. It is an A64 3200+ Winchester, which I have now overclocked from 2.0GHz up to 2.55GHz on 1.5volts. I got a bad week CPU for overclocking so I can't get much higher. In fact I can probably take the voltage back down a bit because it didn't seem to give my any extra o/c headroom. Still, it's nippier, and this time it works