I'm using Windows 7 Profesionell. So I sadly don't have access to Bitlocker.

Truecrypt sugests to use Bitlocker, but since this is not an alternative for me (I can't/won't buy Ultimate) I would like to ask if there are any other Encryption Tools to secure a running system. I wan't to be able to encrypt a whole drive without removing my files/programes there. Is this possible?