Microsoft is sweetening the pot in hopes of getting holdouts to switch from their dated Windows XP machine to something a bit more modern. Last week, the Redmond-based company offered a $50 gift card to those purchasing a Windows 8.1 computer but they’ve since improved that offer in more ways than one. From now through June 15, XP users looking to move to a new system are eligible for a $100 discount on a qualifying machine priced at $599 or higher.