Rather than use bigrodey77 static variable, you can use the WordPress variable $posts_per_page. So to determine the first and last post you could use:
<?php
$postCount = 0;
// Start of The Loop
if (++$postCount == 1) {
// FIRST POST
}
if ($postCount == $posts_per_page) {
// LAST POST
}
// End of The Loop
?>
