Hi. I am using webmon to monitor changes in a website's specific html code. As far as I'm aware this is the only method. Is this true?

I am trying to monitor this webpage - http://tt.tennis-warehouse.com/member.php?u=5543

What I'm looking for is the blue circle in the top left to change to green. This indicates the user is now online.

<div class="bigusername">Topaz <img class="inlineimg" src="images/statusicon/user_offline.gif" alt="Topaz is offline" border="0" />

Is this the line of code I need to monitor?