I don't know what a "clean vanilla install" means.

Here is what I have been doing though...

1) Uninstalled Medieval Total War.
2) Located all Total War files in existence and deleted them.
3) Installed MTW Gold Edition from Eras Pack
4) Downloaded the zip file with the two buttons
5) Set up a "new folder" on the desktop
6) Extracted the two bif. files to the 'new folder'
7) Go into 'new folder' cut the files
8) went to(this is in vista)
C:\Program Files\The Creative Assembly\Medieval - Total War - Gold Edition\campmap\buttons
9) Now Vista asks

There is already a file with the same name in this location.
Click the file you want to keep

->Move and Replace
Replace the file in the destination folder with the file you are moving:
button_ipnext.BIF
button_ipnext (C:\Users\Aaron\Desktop\New Folder)
Size: 1.07 KB
Date Modified: 7/17/2004 3:15 PM (newer)

->Don't Move
No files will be changed. Leave this file in the destination folder:
button_ipnext.BIF
button_ipnext (C:\Program Files\The Creative Assembly\Medieval - Total War - Gold
Edition\campmap\buttons)
Size: 3.04 KB (larger)
Date modified: 4/15/2002 4:10 PM

-> Move, but keep both files
The file you are moving will be renamed "button_ipnext (2).BIF"

10) I click on move and replace
11) Vista asks

There is already a file with the same name in this location.
Click the file you want to keep

->Move and Replace
Replace the file in the destination folder with the file you are moving:
button_ipprev.BIF
button_ipprev (C:\Users\Aaron\Desktop\New Folder)
Size: 1.01 KB
Date Modified: 7/17/2004 3:17 PM (newer)

->Don't Move
No files will be changed. Leave this file in the destination folder:
button_ipprev.BIF
button_ipprev (C:\Program Files\The Creative Assembly\Medieval - Total War - Gold
Edition\campmap\buttons)
Size: 3.08 KB (larger)
Date modified: 4/15/2002 4:10 PM

-> Move, but keep both files
The file you are moving will be renamed "button_ipprev (2).BIF"

12) I click Move and Replace
13) And it's vista so of course...

Destination Folder Access Denied
You'll need to provide administrator permission to move to this folder
buttons
Date created: 5/28/2009 7:53 PM

14) I grant administration access...(speaking to Vista) I AM THE ADMINISTRATOR (got to hate that) and click Continue
15) Vista asks for permission for file operation
16) Permission granted continue




Hope that helps you help me, in case I did it wrong
I'm trying the other solutions you have spoken of Caravel.
I'll post back when I am done.
Thanks again everyone! :)