Reformat Problems?

To make a long story short, I recently was given a Dell XPS T700R Computer and all was well until I installed a Sony Driver Program and it made all my other Drivers go crazy. I have tryed everything and have come to the conclusion that it may be time to reformat. How do I go about doing this? I also have no Dell supplied Disks. I am currently running Windows 2000. Any help would be greatly appreciated. Thanks.