"Reinstalling" the Windows 7 boot manager

I've run into an interesting predicament. I've got two HDD's, one running Windows XP (Primary) and another running Windows 7 (Secondary). I recently installed Gentoo over the XP installation and used the whole disk for the install.

I poked around on Google and saw that Windows 7 creates some kind of boot partition on the primary HDD, however I found that out after I had already installed Gentoo... deleting said partition.

So I've still got an untouched copy of Windows 7 on my 2nd HDD, and when I chainload to it from GRUB, I get an error saying BOOTMGR wasn't found. I can't track down my Windows 7 disk (it was an RC DVD so I didn't keep good track of it, this is my big problem) and I was wondering if there's any way to make a System Repair disk of some kind from an image file, or if I can use my XP CD (or possibly my Vista DVD, it's very scratched but might run) and use that to run the repair utility.

Personally I find it easier to use the Windows Vista/7 bootloader compared to grub, so I would:

Download a working trial disk of Windows 7 and burn it. (Do not worry about trial, we are not reinstalling Windows).

Go to Bios and switch the hard drives around so you boot from the second drive.

Put the Windows 7 disk in and go to Repair the computer then choose Startup Repair.

This should install and setup the Windows 7 Bootloader and configure it for Windows.

Now, install EasyBCD which I think is the best BootLoader Editor.

You may even be able to configure it to boot into Grub off the first disk without problems - however, personally, I would try to just boot straight to Linux from it. I cannot help you here but I know people have been able to do this and not require a reinstall of Linux.

Please try this:

1- boot the windows 7 CD

2- repair

3- click on the cmd option

4- diskpart list volume

5- make sur that c:\ is referencing the volume that contains windows directory, if it is not the case change it to c using assign letter command of disk part

6- now, you are ready to rebuild from scratch

7- go to c:\windows\system32

8- run : bcdboot c:\windows /s c:

9- shutdown -r -t 0

Everything should be ok.