You will need the Windows 95/98 Plus! pack to be able to use the theme.

Extract the zip file to c:\program files\Plus!\themes and make a new folder
for it.
Unzip the file to the new folder.
Inside you will find a file called SimsTheme.theme...double click on it to
start the new Sims theme.

Included are new icons for my computer, network neighborhood and  recycle
full and empty .
There are also new cursors for the mouse and the waiting and application
starting cursors.
This will also be your first chance to hear some sounds from the game as I
have tied several The Sims sound effects and voices to system events.

The theme will change your desktop colors and your wallpaper as well.

Even if you don't have the Plus! pack you can still find the icons and the
sounds (wav files) in the zip file to play with.

This theme was constructed using the evaluation copy of Microangelo,
available from the good folks at Impact software. http://www.impactsoft.com/

These instructions were written by Sean Baity Assistant Producer for The Sims