I believe that the following html changes, replacing lines 19 through 23 in the index file of the main page, would achieve what you are looking for as well (if that is a possibility). Text provided is example only, and font size / color adjustments would be a good idea as well, though I would leave that to the administrative palate.
<td width="63%" height=82 background="/images/adback.gif" bgcolor="#336699" nowrap><font size=1 face="Verdana, Arial" color="#ffffff"><b><font color="#cccccc">Create an account on the forums to submit casual Magic content and engage in discussion!:</font></b><BR> </td><td width=130 height=82 bgcolor="#336699"><img src="/images/trans.gif" width=130 height=82 alt=""></td></tr>