[jeroenhd]

> Then Microsoft added a green start button and dark blue backgrounds and packaged Win2k for home users as Windows XP.

XP contained a lot more than just theme changes. XP solved a lot of compatibility issues that Win2k still had at the time. Running 2000 applications on XP would be nearly guaranteed to work, but Microsoft needed to also get Windows Me/98/95 games and applications to run for consumers.

XP brought a few general improvements such as ClearType and the ability to revert driver updates (which Windows users are still unable to find these days, leading to the "I have to uninstall updates every week or my weird USB keyboard breaks" rants online).

Everything Windows 2000 did good, XP did as good or better. The biggest difference was the UI, but the "classic" theme stuck around until at least Windows 7.

[Max-q]

Wasn’t also the graphics driver moved to kernel space in XP? A good performance boost at the cost of unrecoverable crashes if the driver failed.

[hollandheese]

That was moved in NT 4 actually.

[anthk]

Windows 2000 had a compat mode too and it was to run w9x stuff better than XP itself.