Regular Expression Find and Replace with Wildcards

Hi!

For the world of me, I can't figure out the right way to do this.

I basically have a list of last names, first names. I want the last
name to have a different css style than the first name.

So this is what I have now:

<b>AAGAARD, TODD, S.</b><br>
<b>AAMOT, KARI,</b> <br>
<b>AARON, MARJORIE, C. </b> <br>

and this is what I need to have:

<span class="LastName">AAGAARD</span> <span class="FirstName">, TODD,
S. </span> <br />

<span class="LastName">AAMOT</span> <span class="FirstName">, KARI,</
span> <br/>

<span class="LastName">AARON</span> <span class="FirstName">,
MARJORIE, C.</span> <br/>

Any ideas?

Thanks!