Add Windows 7 VHD to XP

Hi all.
Last month, I had Windows XP SP3 dual booting with Windows 7 Ultimate VHD.
I reinstalled Windows XP SP3 and still had Windows 7 VHD file in drive D.
I has read the previous thread how to add win7 vhd to my pc but my situation is different.

I had tried booting from WINDOWS 7 DVD, press Shift F10 to open Command Prompt, typed diskpart
sel vdisk file=D:\windows7\win7.vhd
attach vdisk
exit

bootrec /rebuildbcd
bootrec /fixboot

then i typed bcdedit
it listed 2 entries : 1 is XP SP3 and 2 is Windows 7 VHD

but after restart, It didn't show the boot menu, It only loads Windows XP

So I need windows 7 boot manager installed on C:, right?

How could I add existing vhd to XP instead of creating a new vhd and installing windows 7 on it ?
Can I install Windows 7 on Virtual Machine in Virtual Box and then copy Windows 7 Boot manager to C in my XP?
Sorry for my English, I am not English speaker.

I have the same problem. Can someone solve it?