AHCI mode gave me two boot options

You to remove the second boot entry you want to edit the boot manager files. There is a command tool for this on the windows DVD, but an easier solution is to use a tool called EasyBCD

Also nice to know: AHCI uses different drivers than IDE. With win7 you no longer need to reinstall your whole OS when you have your boot drive on the controller which you switched from IDE to AHCI. Instead do this:

1. Start Regedit
2. Open HKEY_LOCAL_MACHINE / SYSTEM / CurrentControlset / Services
3. Open msahci
4. In the right field left click on "start" and go to Modify
5. In the value Data field enter "0" and click "ok"
6. exit "Regedit"
7. Reboot and enable AHCI in the BIOS