That's the Media Center theme, not the original XP one. They're similar.
I've used Win 98 for about 6 years, moved to XP for about 2 years, and then saw the light
Many people want to move to Linux, but can't because their parents or other, older people who use their computer can't get used to it, so that's the solution.
I have no idea how to do it on Kubuntu, but that should be similar.
Step 1: icons. Get GnomeXP here. Unpack it to your desktop, then run the terminal. Type in :
Now, go to Appearance in Ubuntu, or Settings Manager -> User Interface -> Icon Theme in Xubuntu. Choose GnomeXP.
sudo cp -r GnomeXP /usr/share/icons
Now you have XP-style icons.
Step 2: GTK2 theme. Download it here. You can use the Metacity theme too, if you like.
Step 3: *Xubuntu only* - xfwm4 theme - get it here. You need just the Royale directory and the xfwm4 directory in it. Unpack to desktop, then type in terminal - (first make sure you're in the unpacked directory)
sudo cp -r XPRoyale /usr/share/icons
Step 4: wallpapers - the original one here, the media center one here.
sudo cp -r Royale /usr/share/icons
Step 5: launchers - create a launcher with the caption "My Computer", choose the icon computer for it (from /usr/share/icons/GnomeXP), with the command : Ubuntu - nautlius / , Xubuntu - thunar / .
Then rename your Home launcher to My Documents or simply create a new one, add a launcher to Trash named Recycle Bin (the command is "nautlius trash:///" or "thunar trash:///"). Now you're done.
Step 6: remove your panels, create one, docked at bottom panel, insert a menu on left side, clock and tray on right side, and windows list between them. You can add some launchers to simulate "quick launch" too.
as the menu icon.
Step 7: *optional* - search for a matching Firefox theme, M$ Office icons for OpenOffice launchers and icons for Pidgin, etc'.
*NOTE* : it's possible to remove the desktop icons background, just google it.
The result: something similar to this -