Why has Microsoft not introduce a major new operating system product since 2001?

Microsoft put Windows XP on the market in late 2001. Service packs and bug fixes cannot really be considered new operating systems - they just aggregate a lot of patches and add a few critical enhancements.

Apple released Mac OS X 10.0 in early 2001 and has released 4 new versions of the product since that time. The operating systems' graphics capabilities amaze MS-Windows users when they see them. The Microsoft platform will likely not have corresponding graphcs and search capabilities for it until 2007. Even then, they still might not be a Mac for Mac OS X of 2005 - or even Mac OS X of 2003.

Linux has been through a couple kernel versions since that time, dramatically increasing its capacities to better support enterprise computing and adding huge performance increases in some areas.

Why has Microsoft not introduce a major new operating system product since 2001?anti virus software

for the fact that it's a closed source OS so development has got to be slower than open source

Why has Microsoft not introduce a major new operating system product since 2001?aurora

Takes alot of time to write a OS, it is not easy task, design, testing, back to design when problems are found. takes alot of time to test and redesign a OS, plus when XP first came out, people did not move to it, because alot of hardware did not work with it, now their is x64 XP, and again, alot of hardware does not work for it, software is slowly getting their,
Because XP is stable enough! BTW Windows Vista (code named: longhorn) is on the way.
I have windows longorn, it is good enough. the designs r perfect. i just answered your question.