The images for the KDE4 sysinfo "My Computer" are stored at
/usr/share/kde4/apps/sysinfo/about/images
-rw-r--r-- 1 root root 4.0K 2008-06-19 11:01 network.png
-rw-r--r-- 1 root root 4.1K 2008-06-19 11:01 mem.png
-rw-r--r-- 1 root root 3.1K 2008-06-19 11:01 launch.png
-rw-r--r-- 1 root root 5.8K 2008-06-19 11:01 inner-bcg.png
-rw-r--r-- 1 root root 2.9K 2008-06-19 11:01 hdds.png
-rw-r--r-- 1 root root 773 2008-06-19 11:01 hdd.png
-rw-r--r-- 1 root root 1.1K 2008-06-19 11:01 dirs.png
-rw-r--r-- 1 root root 2.7K 2008-06-19 11:01 cpu.png
-rw-r--r-- 1 root root 3.7K 2008-11-11 08:11 display.png
-rw-r--r-- 1 root root 591K 2010-07-05 19:05 background.png
1. Make a backup copy of the images, 'background.png' and 'inner-bcg.png'
2. Open them with Gimp > Colorize > Change to your favorite color
3. Replace the original
4. Now open My Computer from Desktop and you should see the new colors.
Right click on "My Computer" and 'open with' > kwrite... You must see a lot of information now on the XML page
/usr/share/kde4/apps/sysinfo/about/my-computer.html