Transactions in Postgres

HI,

I am running Postgresql-7.2 with PHP 4.1.1 and I am beginning to use
transactions inside of a php script:

$Link = pg_connect("host=$Host dbname=$DBName user=$User") or die
("Couldn't connect to the database $DBName");

 $Query = "BEGIN WORK; INSERT into $TableName
(firstname,lastname,emailaddress,comments,created)
values('$Array[FirstName]',
'$Array[LastName]','$Array[email]','$Array[Comments]', 'now()');
COMMIT;";

 // Test to see if the query was succeful or not

 pg_exec($Link, $Query) or die ("Couldn't insert name $firstname");

 if (pg_exec($Link,$Query)) {
 echo "<h1>Insert was successful</h1>";
 } else {
 echo "<H1>Insert was not successful</H1>";

What I am finding is that this query will insert a new name twice in the
database within milliseconds of each other.  What am I missing in doing
this?  Any help is appreciated.

Trevor