windows 7 - BOOTMGR is missing, and no C-drive present

I have encountered a problem that I cannot seem to find any way around. So I turn to you for help.
Read carefully, because this is not the regular “BOOTMGR is missing” problem…

I have a PC where I had one HDD with two partitions (C: and D:) and Windows XP installed on C:. Then I installed another HDD (G:) and on this one I installed Windows 7.

After this I got a boot screen every time I started my computer, asking me if I wanted to boot Win XP or Win 7. And that worked just fine.

Drive 0: 
* Volume C:  XP

* Volume D:  Data

Drive 1:
* Volume G:  win 7

After some time I decided that I had no use for Win XP anymore, so I deleted that partition and made the whole space on that disk available for the D: partition (still named D:). This because I use the computer for making music, and I had numerous music programs and projects pointing at files on D:.

At first everything worked just fine, my computer booted up nicely in Win 7, without any boot menu.

But just recently I had to remove my on board memory and then reinstall them again. After that, when attempting to boot, I get the message: “BOOTMGR is missing” message, every time I try to start my computer.

I have tried to solve it by using the installation CD. Booting from that, and then choosing “System Repair”. After that I just get a message that there is no Windows installed on this computer.
Can someone please help me? I’m stuck here.