I was actually an early adopter with XP, and I can tell you when it came out it had major issues. The IRQ steering, that was suppose to solve many of the BSOD issues due to resource conflicts wasn't working properly for example. In the bios on my kt133a board the IRQs were all different, but in Windows it would keep putting my vid card Riva TNT/2 I think and sound card AWE64 on the same IRQ, meaning the computer would hard lock any time You'd play a video game. Ended up having to force IRQ settings for a long time to work around it.
And there were quite a few differences between Vista and 7, the little bit I'd dabbled with troubleshooting on vista to see what it was like, I could tell a huge difference when 7 came out.
And Windows ME was a mixed back, either it worked for you or it didn't. It was more or less Win98se with the GDI stripped out to bare minimum. Which was ok, if you did only Windows based programs, or hardware. But, if you used a lot of ISA slot hardware, like say good soundcards of the time, or still played some games that used DOS launchers it was craptastic. Not to mention some printers that used generic dos interface based windows driver, the Okidata inkjet I had at the time, for example.