I need a clarification on something. I have a friend who wants to upgrade from Win98 SE to Win XP. He bought the upgrade version and not the full version and now he wants to format his HDD clean and install XP on it. If he does that, i was under the understanding that it will not work. I thought an upgrade MS CD requires that an OS is already present on the system. (i.e. it checks for certain OS files to exist on the HDD). If he formats the HDD clean, will he still be able to install Win XP???? TIA.