Not sure if Vista 32 bit is the same.......but you can try.

BEFORE YOU DO ANYTHING: Go and make a backup of your profile which is located here, just right click on the profile folder and click copy then make a temp. folder on c:\ and paste it there.
C:\Users\(your computer name here)\appdata\local\virtualstore\programfiles(x86)\activision\call of duty 4 - modern warfare\players\profile

1. Go to your COD4 folder located in C:\Program Files (x86)\Activision\Call of Duty 4 - Modern Warfare

2. Right click on the Call of Duty 4 - Modern Warfare folder and click copy, then close that window

3. Right click on C:\ in My Computer and click on NEW and then FOLDER and name it COD4 1.7

4. Now open that folder and right click and paste Call of Duty 4 - Modern Warfare into that folder

5. Now run the 1.6 update and MAKE SURE YOU CHANGE THE DIRECTORY TO THE 1.7 FOLDER YOU MADE!!!

6. Now run the 1.7 update and MAKE SURE YOU CHANGE THE DIRECTORY TO THE 1.7 FOLDER YOU MADE!!!

7. Now go to the COD4 1.7 folder and click on it, then click on Call of Duty 4 - Modern Warfare folder, then right click on the iw3mp file. You can then add it to your QUICK LAUNCH or create a shortcut to your DESKTOP, then you will have to right click on the shortcut and rename it COD4 1.7

YOU MUST RUN THE 1.6 PATCH THEN THE 1.7 PATCH

1.6 Patch http://redirectingat.com/?id=593X1004&u ... .6%2BPatch

1.7 Patch http://redirectingat.com/?id=593X1004&u ... 2Bto%2B1.7