How to reinstall window xp on bootcamp drive that's on Mac OS X

[winneo]

Hi everyone. I am newbie on Mac.About last year, i partition my mac book aluminum to 2 hard disk using boot camp assistance and then installed window xp on the boot camp drive.Yesterday,my window xp can't start and i wanted to recovery,which i don't know how.At that time, i change to Mac OS X and it hang on loading.So i called up the apple, they told me to reinstall the Mac Os X, by putting in the install Mac OS X CD. I followed what they told me and then i can go in my Mac OS X, but when i restart and go the start-up page, there is 2 hard disk, 1 is my MAC OS X , 1 is boot camp which suppose to be my window xp. So i wanted to install window xp to it, so i use boot camp assistance but they told me that "my start-up disk cannot be partitioned or restored to a partitioned disk." Then bottom say"The start-up disk must be single Mac OS X Extended (Journaled) volume or partitioned by boot camp Assistance for installing Windows." Anyone can tell me how i can install window xp in it? I heard people say i can reformat the boot camp drive? But i don't know how to. By the way, my boot camp drive is on Mac OS. So now i have two drives which on Mac OS X. Help me! Thanks for reading and sorry for my bad English.