Is it possible to build a new Win XP MBR? The old 1 was overwritten by Ubuntus GRUB.

Hi there, i have an old PC with Windows XP as original OS. I tried some Ubuntu version (dual boot via GRUB) but i am not very happy with it, so i'd like to go back and start from the beginning. My Windows XP-CD is a kind of recovery version that doesn't offer repair mode (after booting from it) to use the FIXMBR command. It only allows to entirely reinstall XP without any servicepack, this would take me hours and i don't want get back that far to the beginning :smile:
I installed EasyBCD and it seems not to be able to build a new MBR (the original was overwritten by the GRUB dual bootloader of Linux). I browsed the forum a little bit as well as the documentation, did i oversee something or is it simply not possible?
Additional question: I also have an EEC mini PC with Win 7 and Linux mint 17 dual boot via GRUB. I am happy with it, so this (same) question is theoretically: can EasyBCD build a new MBR for Win 7? The PC was delivered without any CD, it even doesn't have a CD/DVD-drive. As far as i know these kind of PCs have a hidden partition that enables you to restore Windows. Does this feature still work, when the original MBR was overwritten by GRUB?
Thanks for your help, yours sincerely, u2.0