As I was upgrading harddisks I thought about giving windows 8 a spin. and got what I deserved. ;-) I had expected Grub to be wiped, however I was a little bit surprised that the existing Windows (Vista) installation (which was automatically integrated in Windows 8 bootloader) did not boot anymore. Vista's automatic system repair failed, manual intervention on the system console (bootrec) seems to have shredded the system (The partition table is messed up.) No data was lost, as I have simply switched back to the old hd again. I will need to re-do the harddisk upgrade, though.