Is it true that Dual Core CPUs works better if using windows Vista instead of Xp?

I read once that Windows Vista has a better control over Dual Core CPUs than Xp. I even read that a dual core CPU would work the same as a CPU of the same GHz but simple core.Is it true that Dual Core CPUs works better if using windows Vista instead of Xp?
well my view is that xp was out before dual core processors were invented so people at microsoft couldn't really design their operating system around dual core processors, but when dual processors came out (around the time vista was in its design state) the people at microsoft were able to design vista around dual cores so they could to co-operate more efficiently with the new operating system rather than with xp.Is it true that Dual Core CPUs works better if using windows Vista instead of Xp?
This is not true as Windows XP has native support of dual core CPUs. I have never seen any evidence to support this claim, but I have seen evidence of XP being quicker than Vista because it uses fewer resources.