Well folks, thanks for the tip's re bluetooth signal strength. It's helped me to sort out my trackpad unresponsiveness. I have followed the tip at http://www.mcelhearn.com/2007/04/19/apple-bungles-bluetooth-in-mac-pro/ (read all the comments before trying this), and bingo my BT signal strength has rocketed by 30dBm or more and the trackpad so far is as smooth as silk. I'm not 100% certain that this is an error on the part of Apple as the article suggests but it does seem to swap the BT signal to an aerial which is at the front of the mac-pro case rather than underneath. For me the effect is to put the antenna much nearer to my trackpad as the mac pro is under my desk. My airport signal also seems unaffected but as I don't use the mac-pro for wireless I can't be sure that its as strong for wifi connections as it was. Ill post a further comment when I have used the trackpad for a while just to be sure.