UnSafedisc 1.5.5 is very easy.
You need only three files from the game to make a fixed exe.
The files you need are
DPLAYERX.DLL (should be in the root of the cd)
GAME.EXE (in your case SIMS.EXE i think, sometimes you have to install the game to get these main exe)
GAME.ICD (in your case SIMS.ICD i think, sometimes you have to install the game to get these file)
Copy these three files together in one Temp-Folder on your HD. Start Unsafedisc 1.55. Click on Decrypt, browse to GAME.ICD, click on OK and wait a few seconds. After that you'll have a TESTME.EXE .
Copy this to your programm-folder. Start it!. If it works (it will do!), end the game and rename it to GAME.EXE (in your case SIMS.EXE) overwriting original one. If you want you can rename the original exe to SIMS.EXE.ORG before it to hold it.
Hope this helps you...
Happy New Year!
EDIT:
Forgot to tell you where you get Unsafedisc 1.5.5
You can use Google for it or try this link
http://unsafedisc.crack.cd/unSafedisc_1.5.5.html