I thought my mission was an easy one:

Code sign an existing MFC application (Metafile Companion) setup installer

I should have known better. :-) I was successful and it really isn't that hard once you find out what to do. But there's the rub - the web is full of options that end up being dead ends. Below are some of the lessons I learned.

Lesson 1: You really can pay $99 for a one-year signing certificate from K Software.

There are other more expensive Certificate Authorities (e.g. VeriSign and Comodo) that charge more than this. But the K Software certificate (issued by Comodo) seems to work just fine. I would recommend using either Firefox or Internet Explorer to place your order and later downloading your certificate so it is added "automagically" to the system certificate store. Also, follow their export instructions so you have a backup of your certificate.

Lesson 2: To see what certificates are on your system, run "certmgr.msc". 

This is how you can be assured...