I would like to install Vista on a second primary partition. XP is already installed. I have read MudCrab's guide, but I would like to know if I can do it in a simple manner using only ADD and OSS. Also I am less than clear about the purpose of hiding a partitions, when I have to do it, as to when mark a partition active So far I would try this way, not knowing if the steps are correct and in the right order: 1. Create an empty booting and system partition for Vista (as explained by k0lo in the other beginner guide) 2. Use OSS selector to hide the XP partition "C:\" and set Active either the Vista boot partition (?) either the Vista system partition (?) 3. Switch off 4. Boot from the Vista DVD and install Vista on the boot partition, then install the rest of Vista on the system partition. Finish! 5. After that I can either boot from XP or from Vista, but I will always have to hid the un-used OS beforehand, and mark sure the system I want to use is active in the OSS window How far I am from a total mess-up?