"No T6 there is nothing on the disk about oem it says XP professional"
the word oem is on the label with the 25 letter key, on the disc of xp professional i don't remember the oem, only on the home version
basically if you bought on box the license, you can install it on virtualbox as many times you like but if it is a label or a sticker on the side of the box, it won't work the way you need it
about support of xp, basically it stopped 2 years ago from the point of view of microsoft, many apps form them are not available anymore in their updated versions for xp, the support untill 2014 is as said only for security patches but some companies will support it at least 2015, so some apps will work well there for a couple years more, still xp is a thing of the past, port what you can to windows 7 and wait to the windows 8 fiasco so next os from them is usable as a xp replacement