Okay, just a note for everyone, just in case: do not
try to install Acronis OS Selector (part of Disk Director) from within Windows 7. First, it will not detect your Windows 7 installation. Second, when I disabled it again it completely ruined my Master Boot Record.
It took me more than two hours to recover the Master Boot Record. Acronis and Microsoft made it very difficult for me to fix it
The bootmgr.exe was totally gone. Then the Vista (the original boot manager was from Vista) recovery DVD somehow set a Dell Diagnostics partition to boot up and my Vista and 7 installations were seen by the recovery DVD, but bootrec.exe didn't recognize them. I tried everything to fix the MBR with bcdedit.exe and it looked good, but somehow it still booted the Dell partition. I ended up using GParted Live on an MP3 player, lol, since I had no USB stick laying around! I could set the boot flag to my Vista drive again and after that the Vista recovery DVD recognized everything and the Startup Repair finally did it's job!
Sorry, for the details, but if this happens to you, then you know how to fix that stuff now