No, no, no. Images are funny, but downloading them takes a
lot of time.

Maybe you just put
<FONT SIZE="+3" COLOR="FF0000">+</FONT>
instead of your <IMG SRC="/images/ok.gif">

and
<FONT SIZE="+3" COLOR="00BBEE">-</FONT>
instead of <IMG SRC="/images/minus.gif">

That looks nice enough.