Windows XP was the kingpin of PCs in the US with 43.1 percent market share. But that's rapidly changing. StatCounter shows that while Mac OS X is creeping up slightly and Windows Vista continues its death march, Windows 7 is on the rise, steadily closing the gap with trusty ole' XP. Last month, XP's share sank to 32.17 percent, while Windows 7's edged up to 30.84 percent, leaving the latter poised to overtake XP -- something the much-maligned Vista never did. And if early numbers are to be believed, it's already happened: StatCounter says that for the first week in April Windows 7's share (among desktops, at least) totaled 31.71 percent, compared with XP's 31.56. Either way, it seems Microsoft has convinced consumers that it's finally safe to upgrade.