How many versions of Windows 7 can a netbook run? Three, and possibly more, according to HP's Kyle Thornton, who recently attempted to "clarify" the situation in an interview with Computerworld. Those include in the main Professional and Home Premium editions, as well as the low-end Starter edition which, among other things, is limited to running no more than three applications at a time. According to Thornton, HP has also been testing Windows 7 Ultimate on its Mini netbook line, although it apparently isn't saying if it actually intends to offer it on future netbooks or not. But that's not all. Thornton also says that HP "hopes" that it'll be able to continue to offer both Windows XP and Vista Business on its business-oriented netbooks even after Windows 7 ships... and ships, and ships.