The most recent test versions of Windows XP show dramatic improvements over beta 2, or build 2462, which Microsoft in March distributed to about 500,000 testers. Last week, I got my greedy, little hands on XP build 2486, one of the most recent versions to include Windows Messenger. What I found in build 2486 shattered my earlier misgivings about Windows XP, when I compared Microsoft's operating system to Mac OS X. In fact, I now would easily give the nod to Windows XP over Mac OS X, which in shipping form hasn't matured as much as Microsoft's beta operating system. Where Windows 95, 98 and Windows Me failed to deliver in stability, running multiple programs at once, or managing memory, Windows XP brings home the gold medal. If anything, I have to fault Microsoft for not delivering these features six years ago with Windows 95. The software giant also finally delivered a robust and stable operating system that is backward compatible with most existing software. Windows 2000, for example, pleased many businesses with its stability but tanked running many consumer software programs and games. I loaded up Windows XP with some of the wackiest stuff I could find and ran into few compatibility issues. Even my daughter's "Sonic the Hedgehog" games, which choked under beta 2, ran perfectly on build 2486. For programs that are cranky, people can switch to "compatibility mode," which tricks the software into perceiving its running on an older version of Windows.