[WetWired]

To access your system by paths instead of parameters, add the following to the .htaccess in the directory containing articles.php , creating the file .htaccess if neccesary:

<Files article> 
ForceType application/x-httpd-php 
</Files>

Then, make a copy of article.php , renaming it to article without an extention. Add to that file before the c= and a= parameters are decoded:

//find the path past this file
$pageName='article';
$pageUrl=$_SERVER['REQUEST_URI'];
$pageUrl=substr($pageUrl,strpos($pageUrl,'/'.$pageName)+strlen($pageName)+2);
$fetchType=0; //default to an index load
if(substr($pageUrl,0,2)=='c/'){
  $fetchType=1;
}else if(substr($pageUrl,0,2)=='a/'){
  $fetchType=2;
}
$partNumber=intval(substr($pageUrl,2));
if($partNumber==0){
  $fetchType=0;
}

if($fetchType==1){
  $c=$partNumber;
}else if($fetchType==2){
  $a=$partNumber;
}

If you use $_GET['a'] and $_GET['c'] or $_REQUEST['a'] and $REQUEST['c'], then use those instead of $a and $c in the last 5 lines.

This will allow you to access articles like:
article/a/100
or
article/a/100.html

and catagories like
article/c/100
or
article/c/100.html

Then, change the code to generate this type of URLs and change all image paths to absolute references.