It's ironic that the Windows OS touted for gaming takes such a performance hit over XP. You would have thought they could have made more of an effort to at least keep relatively the same performance, since this was marketed to gamers (people who do notice performance).
Even a non-gaming OS upgrade like Leopard doesn't have the performance hit that Vista does. Did anyone see that new Mac commercial that pokes fun at the downgrades back to XP? LOL, I've never been a big Mac fan, but MS sure deserves the black eye for this one.