Need a little help displaying rank image for admin only

[Prezident]

OK, here is what I did so far, but I will add a couple questions afterwards.

PHP Code:

$RankNum = $post[posts];  
if ($RankNum > 500) {
$rank = "<img src=\"images/ranks/gen.gif\" border=0>";
}
elseif (($RankNum > 400) && ($RankNum < 499)) {
$rank = "<img src=\"images/ranks/col.gif\" border=0>";
}
elseif (($RankNum > 300) && ($RankNum < 399)) {
$rank = "<img src=\"images/ranks/ltcol.gif\" border=0>";
}
elseif (($RankNum > 200) && ($RankNum < 299)) {
$rank = "<img src=\"images/ranks/major.gif\" border=0>";
}
elseif (($RankNum > 150) && ($RankNum < 199)) {
$rank = "<img src=\"images/ranks/capt.gif\" border=0>";
}
elseif (($RankNum > 100) && ($RankNum < 149)) {
$rank = "<img src=\"images/ranks/1stlt.gif\" border=0>";
}
elseif (($RankNum > 75) && ($RankNum < 99)) {
$rank = "<img src=\"images/ranks/2ndlt.gif\" border=0>";
}
elseif (($RankNum > 50) && ($RankNum < 74)) {
$rank = "<img src=\"images/ranks/sgt.gif\" border=0>";
}
elseif (($RankNum > 25) && ($RankNum < 49)) {
$rank = "<img src=\"images/ranks/corporal.gif\" border=0>";
}
elseif (($RankNum > 1) && ($RankNum < 24)) {
$rank = "<img src=\"images/ranks/private.gif\" border=0>";
}
else {
$rank = "<br>";
} 


I would like to be able to exclude myself from being assigned a graphic related to my rank based on the amount of posts I have.

Also, there might be the rare case that I would want to give someone a custom rank, and maybe have a custom graphic associated with that and over ride this mathematical part of it.

Is it possible to relate the graphics to the user title rather then how many posts they have?

Thank you so much for the help, you are awesome.