For starters AB the vista boot manager sucks and will almost always bork the xp install eventually. While benching I only ever have one sata port goin to only one hdd with one os on it. Sorry if that seems to simple but with the classy and its only liking one or two of its ports goin to drives, I thought I should mention it.
Secondly, running 01 in xp is key unless I missed somethin.....05 in vista, and 7 for 06 and vantage.