You're executing the sql statement but you're not retrieving anything. You have to fetch the results into something like an associative array, so you use mysql_fetch_assoc(). Try this:

[php]
$Table = 'user';
$name = 'rootx';
mysql_connect($DBhost,$DBuser,$DBpass) or die("Unable to connect to database"); //connecting to the database using the variable set
@mysql_select_db("$DBName") or die("Unable to select database $DBName"); //at connection to the databse select DBNAME (phpforms) or tell that it couldnt connect
$sqlquery = "SELECT COUNT(user_name) as user_name FROM $Table WHERE user_name = '$name'";
$results = mysql_query($sqlquery);
$user_count = mysql_fetch_assoc($results);
echo "current user name " . $_POST['usr_name'] . "<br />";
echo "query returned " . $sqlquery . "<br />";
echo "query returned " . $user_count['user_name'] . "<br />";
[/php]

Also, don't retrieve form variables as $_POST[whatever], use the apostrophes like I did in the code.