I presently have Adobe Acrobat 9 Standard on several PCs. I would like to upgrade to the latest version, and I see it is possible to do that, which is great, so I can pay for the upgrade price and not the full version - however, my question/concern is - after I have the upgrade, in the event of having to re-install the software, is it necessary to first install the old version, Acrobat 9, and then install the upgrade XI over it, or am I OK with just installing XI? If I don't need to maintain Acrobat 9 then that's one less thing to worry about. I tried finding this on Adobe but didn't mention anything either way. If you can provide a link even better! Thanks!