nimd4

Basically the procedure is as following (had to use another file for the example, because I've already changed permissions for mapisvc.inf)..

1. Turn off your User Account Control (UAC), it's easier... Check out the help file, it's stated there; When viewing the Security tab for the file Properties, click on Learn about access control and permissions:
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   • The help file Note'll tell ya: "If this button is UAC protected, you might not be able to modify any security settings. However, you can at least view them by using the Advanced button."
     
     
2. Then click on Advanced, select the Owner tab, click on Edit, select your Username (your current Windows account), then Apply & Ok. You'll have to clear a prompt (Ok).
   
   
   
3. Ok again and then select your Username (the current Windows account) & click on edit:
   
   
   
   Select your Username and checkmark Full Control. Apply & Ok.
   
   
   
   You'll have to clear another prompt (Ok).
   
   
   
   That's it, your're good to go! :d
   
   

Btw., check out some guy's notes too; Links:

Running Office 2003 on Windows Vista and running other applications that work on Windows XP on Vista

& Loading Office 2003 into Vista and fixing the problem with the EULA always coming up.

ps. I'm gonna try and edit this post so that it'll be more readable...