Hm that's odd, I wonder if the actual paths have updated. Do either of them boot?

If not, just edit the menu items in grub manually to match the proper path by replacing the sdb references with sda.

Sweet, congrats! Now you have to decide if you want to let sleeping dogs lie or continue on and use EasyBCD to relocate Win 7's bootloader to sda. Just remember if you do, Windows 7 is gonna eat the grub and destroy all your hard work. :)

Let me try to see if I understand. Please correct me if I'm wrong.
- 7 has a loader, which is a program that needs to be run in order to start the booting process of the OS (where is the xp one?).
- In my case, it somehow got into the wrong hard disk.
- The only way to place it in sda is to use easyBCD.
- This will overwrite grub, which will have to be reinstalled using that same tutorial.
- On the other hand, installing grub that second time won't overwrite the 7 loader.

Sorry, ran to the store. You're almost there, your last two assumptions are incorrect. Here's the deal, somehow the Win 7 BCD was installed on the sdc 2GB drive (I'm talking your original config) instead of the sda 2GB drive. However it got there is irrelevant at this point for our purposes.

This is the long and short of it, if you want to have all systems booting off the same drive these are a couple options:

a.) Boot into Windows 7, install EasyBCD and move the Win 7 BCD off that 2G on sdc and back onto the MBR of sda. Doing this will destroy the grub, there is no reinstalling of grub because (I'm pretty sure of this) they will not exist on the same MBR. If you take this path, you won't be using grub anymore because the BCD will overwrite it on the MBR.

b.) Free up some space on sda (possibly through lvresize in Ubuntu), carve out another small boot partition for Windows BCD to live on, and configure grub to chainload.

In either case I have a more urgent matter: windows 7 boots, but xp doesn't: it says "boot.ini not valid, booting on c:\windows", and then in another screen, 2 seconds later, "windows wasn't able to boot because the following file is missing or corrupted: <windows root>\system\ntoskrnl.exe. Please reinstall a copy of the file above."
Any idea how to solve that issue ?

That should be pretty easy to fix, most likely the ARC path is just screwed up. You should be able to get to your C: drive for XP within Windows 7 if I am not mistaken. From there just modify the boot.ini and make it look like this:

I have booted into 7. Where can I access the xp C drive ?

The instructions for Vista are basically identical in Win 7:

http://windows.microsoft.com/en-US/w...smount-a-drive

If it's not already showing up as a drive in, "Computer" then follow the steps in that URL, modify boot.ini with the correct ARC path.

As a matter of fact, if you have storage somewhere you can always share the same partitions between XP & 7 since they both use NTFS. So no need for data duplication between Win installs. :)

By the way, Windows 7 also allows you to virtualize XP within in.

P.S. You may be going off on a tangent here, since boot.ini will no longer be necessary if you move BCD to sda. You'll be able to configure it in EasyBCD to bootstrap XP directly. *I think*. In any case, it won't hurt to check the ARC path and verify it is correct in case it is still needed for some reason after BCD takes over.

Okay, windows xp is booting now.
I will just ask one more question and leave it for a while (I'm going to eat). There will be the loader issue left to take care of.

My question is, how can I change the timing before automatic selection and the order in the list?
(I also have a small concern, but this has nothing to do with that thread. Is there no security way to prevent the access of xp files without the admin password ? (although it was useful in this case, one could easily think of the potential danger it creates)).

Thanks a lot for your help Brocifer.
Thanks for your help too tregedar.
Glad it's over.

This should help you get the rest of the way as far as the XP bootloader timeouts and selections. If you're talking about grub, I would check the man page.

By default you should be getting prompted to take ownership before modifying any files you mount from a separate Windows install. If you weren't that's kind of strange. I'd google NTFS permissions if you're not sure.

By default (assuming Windows 7 was a fresh standalone install) they will not be sharing the same local SAM db. If you don't want the XP files to be seen from Windows 7, simply umount the XP stuff. Regular users cannot mount drives. You're NOT letting your regular Windows users log in as administrators... are you? :)

Looks like this is sorted at last.

If so, Bob32 please mark this thread as SOLVED (In Thread tools, above).

And thanks to Brocifer for the windows expertise.