Mouse Issues Please Help!

[throosh]

I bought the Penumbra Collection PC DVD and installed it. After it all installed I hooked the games up to steam and ran them, everything seemed fine and was working. Except whenever I go to play the games (doesn't matter which of the three), the mouse lags terribly whenever I attempt to look around and move the camera. This completely hinders my gameplay. I have lowered the video settings and it still does this to the same effect. I have a more than capable graphics card, however I am using a single core processor. I know that should create some problems, but it shouldn't lag my game like this, when I am able to run other steam games on full settings with no lag at all (even with physics). I appreciate that help and hopefully someone has some answers.