Follow these steps exactly and you should be fine.
Step 1: Make sure you have your Windows disk. I personally delete everything I don’t need, and uninstall all programs that I don’t use. I then make a list of all the programs I still have installed and download all the installers I will need. Also download Spybot Search and Destroy and Ad-Aware but do not install them. I then backup all my important data and all the installers onto a portable hard drive – if you don’t have one you can build one or you can use DVD’s or CD’s. Make sure you have everything backed up and then disconnect the portable hard drive.
Step 2: Insert your windows disk into the Master CD drive (if you have more than one) and turn the computer off. Make sure you are disconnected from any networks. You will need to have your cd drive selected as your first boot device. If it’s not already selected, you will need to go into your bios and set the boot priority to cd/hdd, then with your Windows cd in your cd drive, save and exit bios.
Step 3: Turn on your computer. A screen will come up saying “Press any key to boot from disk”. Press any key (where’s the “Any” key gone?!). Now wait about 10seconds for the setup utility to be loaded. When asked if you want to set up or repair, hit Enter to set up Windows. Read the license agreement and hit F8 if you agree. If the setup program detects an existing installation of Windows and asks if you want to repair it, hit Esc to skip the repair. The setup program will ask you where to install Windows. Highlight the existing “C: Partition1” partition and hit D to delete it.
Hit L to confirm. Next, hit Enter to install Windows on the “Unpartitioned Space”. Format the space as NTFS – You will get an option to choose full or quik format. My experience is that quick format is for disk that have previously formatted. If the disk has not been formatted, then you will have to use the standard format option. Usually you will get a popup message “This disk can not be quick formatted” or something along that line. Then continue the installation. Please note: During the installation process, your computer will reboot. You will then see a message to press any key to boot from cd. Do not press any key a second time, otherwise the installation will start from scatch again. Complete the next several screens on the setup process and make sure you do not leave the administrator password blank. After following these steps, setup should be complete.
Step 4: Firstly you should install your antivirus software, Spybot S&D and Ad-Aware. Also enable the windows firewall by going to Start>Control Panel>Network and Internet Connections>Network Connections (icon on the bottom-right)>Right-click the Local Area Connection>Properties>Advanced tab>Check the box next to “Protect my computer and network…”>OK. After this has been done, install all updates from the Microsoft website (including windows XP service Pack 2). Then install all drivers from your motherboard utilities CD. Now it is time to install your programs.
Step 5: Enjoy the brand new feeling of your Reformatted PC
At the end of your formatting do check around here for some good software to stay free from spywares and malwares.
Hope this tutorial helps.