Windows Vista came out (with an instant patch for all the big fail) and pretty fast they came out with Windows 7. . .what like 2 years ago or so? and We're talking windows 8 now =,=
Windows XP was an abnormality, let's take a look at the time between each OS (blatantly copied from wiki):
1985 November 20 - Windows 1.01 (2 years)
1987 December 9 - Windows 2.03 (2,5 years)
1990 May 22 - Windows 3.0 (3 years, can be disregarded since NT OS was a parallel production, around 5 years of win 3, before win95 is released.)
1993 August - Windows NT 3.1 (2 years counting win95, 3 years if only counting NT4)
1995 August 24 - Windows 95 (3 years)
1998 June 25 - Windows 98 (2 years)
2000 February 17 - Windows 2000 (NT5) and: 2000 June 19 - Windows Me (1,5 years for win2k and around 1 year for win Me)
2001 August 24 - Windows XP (6 years)
2006 November 8 - Windows Vista (3 years)
2009 July 22 - Windows 7
As you can see, the biggest gap next to Windows XP if you don't count the parallel development of NT systems, is between Win 3.0 and Win95 (5 years).
Otherwise 2 -3 years between the release of a new Microsoft OS is actually very normal.