I have Windows 8 CP installed on my PC but because I also needed Windows 7 now, I installed on a VHD.

Now the Windows 7 install replaced the Windows 8 BootMgr with the Windows 7 one. My question is: how can I get the Win8 one back?

Just plug the Win 8 DVD in and do the repair install. The MBR should be repaired without doing anything else.

By the way the next beta, Win 8 RP is due to be released, probably on June 1st. This will require a clean install so be prepared. You will most likely have to clean install both OS's.

Thanks for answer, Ted. I'll have a try. Thats so kind of you.