After mucho testing I have come to the conclusion that when running SETI there is no better OS to use than WinXP (32bit).
WinXP (32Bit - Home Edition), WinXP (64Bit - Professional), WinVista (32Bit), Win7 (32Bit - Home Edition) & Win7 (64Bit - Home Edition) - the best I found was good old trusty WinXP.
So, hust ordered another WinXP Home Edition and will remove WinXP Pro from my Asus RE3 when it arrives (after completing any outstanding work from SETI & Climate Prediction).
As stated Win Xp (32bit - Home Edition) is the best for running SETI.
Hmmmm probably have to rethink my setup after that, thanks for taking the time to research it Mr Loudbob sah.
Oh 'eck like, 32bit win xp home means 3 gb memory limit doesn't it arghhhh.
Then there's the joys of trying to marry an sr2 with xp and oh noes.