Problem of Having XP & SUSE both installed

i had both XP & SUSE installed..
xp doesnt instlall itself in one boot.
thats why when i tried to format xp & planned to do it later for SUSE..
things went wrong..
after formatting c drive & copying file xp tried to reboot..but..there is suse..though grub is destroyed..
stopped..
if i gave boot from CD...things started from beginning...
i needed to attach my 500GB harddisk with friends SATA port,copy all...then deallocate( not formatted ) using diskmgmt.msc from system32.
then again  in my  motherboard,install XP.
XP doesnt support multi-OS environment....