Yes, you can restore grub to the mbr. Download and burn the latest stable version of SuperGrub live cd iso. Use this to boot into the Mint install after you have loaded Windows. Do not
try to fix anything with SuperGrub, just use it as a boot cd.http://download.linux-live-cd.org/Super ... sgd/cdrom/
From the Mint desktop, open a terminal and type:
Substitute the correct partition in the root command above. Example: If the Mint /boot folder is on sda5 the above command would be root (hd0,4). Always 1 less than the sda designator.
In a terminal type:
gksu gedit /boot/grub/menu.lst
This will open the menu.lst for editing. At the bottom of the list put the below boot stanza in for Windows. I am assuming Windows is on the first primary partition of the first disk.
title Windows XP
Save and close. When you reboot you should get the nice grub menu and be able to boot into Mint or Windows.
One more chore you will have is to correct the /etc/fstab file, if you are still using UUIDs. Any partitions you have touched will have changed UUIDs. If this is a problem for you post back when you get to that point and I'll help you fix it.