Excellent hack, but I'm using Glop.org's gamercards instead, as they doesn't take up as much space.
Code:
<if condition="$post['fieldXX']">
<a href="http://live.xbox.com/en-US/profile/profile.aspx?pp=0&GamerTag=$post[fieldXX]" target="_blank"><img src="http://www.glop.org/gamercard/card/$post[fieldXX]-forum.png" border="0"></a>
</if>
See
www.glop.org/gamercard for more designs.