How do I change the partition that Windows 7 boots from (the "system" partition)?

Question

(I've searched around but most cases deal with having two hard drives, not two partitions on one hard drive.)

My 1TB hard drive has two partitions: one for Windows XP and one for Windows 7. The Windows XP partition was created first, before the Windows 7 installation. I'm trying to delete my Windows XP partition but I find that I cannot format it from Windows 7 because this partition is still the "system" and "active" partition. I've tried changing the Windows 7 partition to "active" and rebooting, trying to repair the installation with the Windows 7 disc (to add the "system" data to the Windows 7 partition) but that just sent me through a nightmare of "BOOTMGR is missing" and my Windows 7 partition suddenly becoming RAW format, which I just recovered from (dodged a bullet, there).

My question is: how would I make my Windows 7 partition the "system" drive, removing the reliance on the Windows XP partition so I could format it?

I have my original Windows 7 installation disc and an Ubuntu 12.04 livecd at my disposal.

My disk management screen:

Answer 1

From XP

Open up cmd and type

diskpart

and then

list partition

Make note of the number of the partition that you want to mark as active.

type

diskpart

and at the diskpart prompt

select partition *the partition number you wrote down*

at the diskpart prompt

active

Now use bcdboot.exe to copy the Windows 7 boot files to the new system partition.

Bcdboot D:\Windows /c C:

Bcdboot copies the required boot environment files for Windows 7 to the C: partition, and creates a new BCD store to boot Windows 7 from the D: partition.

Now The legacy boot files are: NTDETECT.COM, NTLDR, and BOOT.INI. To copy these hidden files from the root directory of the legacy OS partition to the new system partition, execute the following commands:

xcopy /h C:\NTDETECT.COM C:
xcopy /h C:\ntldr C:
xcopy /h C:\Boot.ini C:

Now reboot to windows 7 to establish the new system partition. This i believe should fic your issue. To see where i got this answer ho here: http://technet.microsoft.com/en-us/library/ee829686(v=ws.10).aspx#BKMK_Step1

Since youre not going to dual boot XP and 7 you should not have to do anything after rebooting to windows 7. Then you should be able to delete the XP partition.

Answer 2

If your machine list both the operating systems just after the POST check when you start the machine, try the following:

Under system properties, in the "Advanced" tab, choose "Startup and Recovery" option, set windows 7 as a default operating system and ucheck the list the operating systems checkbox, then reboot the machine.

if the the machine does not list the windows 7 after the post and the "Boot Mgr" error still persist, you will have to recover your startup files using the windows 7 disc.