Ok, so you can see by now that there isn't much variation between operating systems. One thing I encountered was when testing the HighPoint cards in Vista (32 or 64 bit), if the Nvidia RAID controller was enabled in Device Manager, the CPU usage was stuck at ~25% regardless of the task, which had a negative effect on the results. I had to disabled the Nvidia RAID controller to eliminate this CPU usage. This was due to a driver conflict that HighPoint will be rectifying on the next driver release.