Hi you may have missed this
IF YOU HAVE THE VISTA SP1 INSTALLED: - This will not work if you have SP1 installed unless your Vista installation DVD includes the SP1, or you create a Vista SP1 slipstream installation DVD (See below). When the SP1 is installed, it will give Vista a newer version number than what is on the original Vista installation DVD.
- You can only do a Upgrade install if the currently installed Vista is the same or older version than what is on the Vista installation DVD.
- To create a Vista SP1 slipstream installation DVD to use to do a Repair (upgrade) install, see: How to Create a Vista SP1 Slipstream Installation DVD . Note that this does not always work to use for a Repair install.
- Another option is to uninstall the Vista SP1, then run the Repair install and install the SP1 again afterwards. To uninstall the SP1, see: Microsoft Help and Support: How to uninstall Windows Vista SP1 as a troubleshooting step
IF YOU HAVE THE VISTA SP2 INSTALLED: - This will not work if you have SP1 and SP2 installed unless your Vista installation DVD includes SP2.
Be sure to backup any important data you have, just in case something goes wrong during installation. You may need to reinstall some of your drivers. You do not want to do this if you are
dual booting with XP and Vista was not installed as the primary boot drive. It can cause XP to not startup anymore.