Windows XP performance

Psychotria writes: "I have a Windows XP box that I use mainly for games. In the last couple of months I've noticed a decrease in performance (for example, frame-rates are lower). I don't think this is due to any additional software being installed (as I mentioned, I only use the machine for games). I reinstalled XP and the problem went away — until the Windows updates were installed. Now, the frame-rates in my games have dropped again. Additionally, svhost spends the first few minutes after booting at 100% CPU. I don't want to seem paranoid, but has anyone experienced this? Is it possible that a "performance decreasing" feature has been added to XP to encourage users to upgrade to Vista? I'd like to hear of any similar experiences."