The most common way of starting brand new (assuming that is what you're trying to ask), is to boot up your PC with the OS (I'm assuming Windows XP) CD in your CD-ROM (Making sure the CD-ROM is the boot device. Consult your motherboard manual if you're unsure on how to perform this task).
Afterwards, take a look at this awesome
step-by-step guide
The power of Google helped me help you!
As the guide indicates, you should update Windows immediately by visiting the Windows Update website. Other devices such has video card, printers and even the motherboard may require driver updates as well. You can visit
www.driverheavendownloads.net for a list of drivers from major manufacturers. If you need help with this part, please try to identify the following components to the best of your ability (including model number and manufacturer):
- Motherboard
- Sound Card
- Video Card
- Printers, scanners etc..
- Anything else you have.