Rebooting computer:s

[Matty.]

Hi, I'm trying to reboot my computer but i'm having problems. I have a windows xp disc that I use , when I put select new instillation and I put in all the details etc the computer re starts and it says ' re install windows' but then it says ' you have two operating systems' , and then when I try to carry on it says I have an error. Can any one help me totally reboot my computer.
Many Thanks Matty.
EDIT: I think I mean format my hard drive?

 

[wasisnt]

It looks like you installed a second copy of Windows when you were trying to do a new installation. There will be a point when it asks you what partition you want to install Windows on and you will get an option to format. Dont pick the leave partion as is option. Do the format and then it will start installing a fresh copy of Windows. I recommend formatting NTFS and do a full format rather than a quick format.