I wasn't able to find any good looking, complete icon pack for actual KDE, that mimics look and feel of Windows 2000.
So I decided to create one.
This icon pack is based on icons found in GTK98, Chicago95 and GNUStep icon packs and on icons published at Alex Meub's Windows 98 Icon Viewer website.
This is only an iconpack. If you want to enjoy full Windows 2000-like experience, I recommend to use this iconpack in combination with "MS Windows 9x" widget style and "Reactionary" Plasma shell theme.
Installation: copy Memphis98 folder to ~/.local/share/icons/
Released packages available here.
Enjoy!