Hello guys! I USE VISUAL BASIC 2008!

The problem is that I have a plain text file in which TAG's have that the user can customize. So far so good. Everything is saved in text file, like this:
example:

Code:
<tag1> = http://www.vbforums.com/
<tag2> = http://www.google.com.br
<tag3> = http://www.youtube.com.br
Anyway, it's a huge list.

There's a RichTextBox in this Form. I want that when user writes some of Tags (for example <tag1>), the same be replaced by what is after the equal sign (in the case, http://www.vbforums.com/).

EXAMPLE:
Code:
Hi! I'm fan of <tag1>
BECAME:
Code:
Hi! I'm fan of http://www.vbforums.com/
Is it possible?
Grateful, RickHB.