August29
First of all, by reformat ur Windows, all the data in the same partition with Windows will be erase. So, if u wanna save ur files, make sure they have been moved to other partition. Here is step by step on how to reformat ur Windows…
1) Insert ur Windows XP CD in the CD-ROM drive. Reboot ur computer.
2)Make sure ur computer is set to “boot from cd” (tips: it can be done by pressing “F12″ key while computer is starting or u can manually config it in BIOS)
3)If u are in the correct way, u should see this menu

4) Then, press any key to boot from cd
5) Here is the standard guide, mean that if u r using SATA, & need to install SATA driver, u should do some other steps, google it for more info
6) Then, come the delete and creating the partition steps. If u wanna reformat a whole hard disk, just simply delete (by pressing D and L to confirm) the existing partition. But, if u wanna only delete partition that contains Windows, select that partition and delete, leave the other partition as usual.

7) When all the deleting & creating process is done, now we can install Windows files in the new created partition.
8 ) When it comes to the menu weather to choose “NTFS” or “FAT32″, I recommend u to choose NTFS for some good reasons. Then, press “enter”
9) After the partition is formated, Windows XP will begin instalation. The computer will reboot. This time, when it comes to “press any key to reboot from CD”, ignore that command. Now, the screen will look like this:

10) Here, it will takes some time to install the OS. When it comes to the “entering product key”, please proceed and then press next… next… next…
11) If there are no error in installation process, the reformating Windows should be ok