Windows 2000 was the last good Microsoft OS. XP took 2000 and forced IE into it and moved the video to a lower layer for performance which reduced security and stability.
I disagree. Moving from Windows 2000 to XP reduced the boot time by a factor of 10x, which was a very good benefit for my role as a road warrior on my PIII Dell laptop. Stability was about the same and compatibility with high speed graphics for non linear video editing was a very welcome addition.
Sure, Windows 2000 was a quantum leap in stability when compared to the former "desktop OSes" 95 thru 98SE, but it required an equivalent quantum leap in hardware. IMO far from the best OS from Redmondland.
Years earlier, a similar quantum leap was the introduction of DrDOS 5 (not Microsoft) and its much better usage of the upper memory area - especially after the Microsoft's 4.0 fiasco.
XP simply moved the login screen earlier so yes it booted to login faster but after that you got to watch the hard disk blink while you tried to work as it kept starting other services as you were logging in. I could get older slower hardware to boot to usable 2000 faster than newer faster hardware with XP.
XP fubar'ed the IRDA file transfer (OBEX) so my HP capshare quit working and if you tried between 2000 and XP you had to retry twice.
XP messed up USB to where it would occasionally create duplicate USB storage devices requiring manual clean up
XP removed support for the 'swappiness' (using the linux term here since I can't recall what the reg key was called) so with VMware workstation or Player where I could run 4 guests at a time the same hardware with XP could only run 2 because it kept trying to swap them. I had to double ram and add a separate small drive for swap to get the same performance.
XP/2003 server introduced a bug into typeperf where you would get negative cpu usage % numbers if you used a wildcard (microsoft issued a refuse to fix, use this workaround instead for my case)
XP embedded would not work from a read only drive where 2000embedded would.
The move of video and other user processes to a lower ring made XP/2003 less secure because it was easier to get malware in.
And of course the worse, forced integration of IE to win the court case so now you had a huge security hole that existed for years making it extremely easy for anyone and their brother, monkey, dog or cat to infect systems.
Windows 2000 IE/OE were optional you could install them if you wanted and yes, you could actually remove them though it was easier and quicker to just reinstall but xp was when they really integrated the two to make the huge hole risk IE was and even made some later XP/2003 patches refuse to install if the outhouse express .exe had been deleted (and WFP db edited to prevent the OS from putting it back of course) even if said patches were unrelated to IE/OE.
Many say SP2 was a lot better but by that time I had given up on XP myself and was no longer involved in anything desktop support related so I'm only familiar with the server 2003 issues such as typeperf, TCPChimney, etc.