Changing Windows icons

So I have some nice Icons I would like Windows to use instead of the standard ones. For example I would like to use my icon for all word files instead of the standard one, How do I get windows to use them? Thanks for the help.

Found the answer, guess I should have used the forum search better.

4th post of this thread
You don't need to creat a .dll, just have .ico files, but maybe the .dll way is better??

I used some icon studio program a long while ago to make myself a .dll file with all custom icons I like. It is easier now, but I can't remember what software I used.