you all got it wrong :-p After NT4, there was windows 2000 which was NT 5. Windows XP is after Windows 2000 (NT5). Vista is after XP (6). then we now have win7. However, winver shows 6.1 where as vista is 6.0. in deep down, Win 7 is very nicely done well refined viata :-) (thus 6.1).