According to this story on ZDNet, Windows 2000, which ships next Thursday the 17th, contains 63,000 bugs in this initial release. Their source on the story is an internal Microsoft memo, which says that 28,000 of these are likely to be "real" problems. Microsoft was quick to defend the OS, saying that 750,000 testers agreed that it was ready for prime time, but knowing previous releases from the company, you may want to wait before upgrading.