Good question, isn’t it?  Although Microsoft has listed a set of drivers that will prevent you from being offered SP1, it’s not always clear why a user can’t get it.The service pack is being withheld from machines containing one or more of the listed drivers, because, as Microsoft put it in a support document, “these device drivers are problematic on Windows Vista-based computers when you update to Windows Vista SP1.”That made an industry analyst wonder about Microsoft’s driver-testing process. “When Microsoft