“Posts Paged” Problem

I’ve setup a small photoblog using WP and I want the frontpage to display ONLY the most recent post in a specific category. I’m close to acheiving what I want, but I’m having some troubles.

This is the code I have in my index.php:

if (empty($_SERVER['QUERY_STRING'])) {
$cat = "1";
}

this only works as intended if I set Options>>Reading>>Show Most Recen 1 posts paged. But when I set it to ‘posts paged’ it also affects another page on my site…specifically this one. There are actually 13 posts in cat=1, but with posts paged it only displays 1.

I hope my dilemma is clear enough that someone may have some insight. I tried searching, but didn’t really see anything relevant.