How do i get windows back on my imac

[Macer]

I installed windows xp sp2 ok on my imac, i then tried to update it to vista beta 2. The boot up didn't work so i then deleted the partition windows was on. I think one of them is an EFI partition i am not sure but it was 128mb. Now i only have the 200mb EFI and MAC OS X on one which is about 180gb and a 50gb for windows that i can't reinstall back on too. How can i get windows XP back on the imac. I have tried to remove the partition through boot camp but it keeps telling me to put my password, even after i put the correct password in. Any ideas. Oh one last thing how many post do you need to post before you can put an advert into the market place section.