For the Blix theme...
Replace this:
<p>
<input type="text" name="securitycode" id="securitycode" size="30" tabindex="4" />
<input type="hidden" name="matchthis" value="<? echo $antiselect; ?>" />
<label for="securitycode"><img src="<?php echo $_SERVER['PHP_SELF']; ?>?antiselect=<?php echo $antiselect; ?>" width="125" height="40" alt="Security Image" border="1" /> <small>Anti-spam word (required)</small></label>
</p>
With this:
<p><label for="securitycode">Anti-spam word (required)</label>
<img src="<?php echo $_SERVER['PHP_SELF']; ?>?antiselect=<?php echo $antiselect; ?>" width="125" height="40" alt="Security Image" border="1" /><br />
<input type="text" name="securitycode" id="securitycode" size="30" tabindex="4" />
<input type="hidden" name="matchthis" value="<? echo $antiselect; ?>" />
</p>