Before scaring someone (who has said that they don't know a lot about computers) and recommending they reinstall their operating system lets try this first.
Johnboy, go to your main menu and go to the options.
Put all the graphic settings down to their lowest setting, turn off Antialiasing and Anisotropic filtering and see how the game runs.
If it runs okay but looks pretty bad then start twiddling with the settings till you get a reasonable balance between graphics and performance.
If however the game runs bad even with all the graphic settings at the minimum then you will need to tweak your computer somewhat as Metroplex and Gatts suggested.
Let us know how it goes.