I find a bit strange that noone allready had the same problem as i had..... However, I have a solution know: The Problem was that vmware workstation asked for the administrator account whitch is not available on vista. Even if you have only one user who is in the administrator group, the account is not accepted by workstation as an administrator account. So you have to activate the administrator account. On vista home premium you have to go to c:\Windows\system32. in this folder you have to look for the file "cmd.exe". Do a right click on this file and choose "execute as administrator" from the context menu. CMD opens. Now you have to enter the following: "
net user Administrator /active:yes". Now you log off your computer and reboot. Now you have to choose this activated administrator account. Only with this account you are now able to convert the computer in a virtual machine....