Question about reputation digital value color

[gtsch]

I modified the postbit legacy template to display the digital value of a user's rep...

 <if condition="$show['reputation']"><div>Reputation: $post[reputation]<br /><if condition="$show['reppower']">$vbphrase[reppower]: $post[reppower]</if>$post[reputationdisplay]</div></if>
                <div>$post[icqicon] $post[aimicon] $post[msnicon] $post[yahooicon] $post[skypeicon]</div>
            </div>

I want to make it so that if the user is in the positive, the number appears green, and in negative it appears in red. Can anyone help me with this? I'm stumped.