I installed KDE4 Desktop on Ubuntu 7.10 as follows:
Added the repository:
deb http://ppa.launchpad.net/kubuntu-members-kde4/ubuntu gutsy main
sudo apt-get update
sudo apt-get install kde4-core
Then I checked the available widgets in add widget dialog. There are very few.
I searched on Google "Get more widgets KDE4" and found this site.
Installed the following package:
sudo apt-get install extragear-plasma
Now see my KDE4 desktop with some of the widgets running:
There is comic strip widget at the top.
Below that there are two more:
Picture frame on left in which sideshow is running and