Running Screen Scraper Effeciently on a server

i'm running screen-scraper on a server with
Windows Server 2003
Xeobn 3.2Gig
512mb of ram

I have a scraping session that takes 8+ hours to run. What is the best way to optimize screen scraper. What is the best way I can take advantage of the server. Is there a settings file i can edit to take full advantage of the hardware i am using. the guts of the scraping session is as follows
[quote]//Assign session its own thread
$session->setDoLazyScrape(true);

//Check for errors from scraping server
if( $session->isError() )
{
$logger->err("__LINE__:" .$session->getErrorMessage());
die("__LINE__:" .$session->getErrorMessage()."\n");
}

//Tell the session to scrape.
$session->scrape();

//Disconnect from the server.
$session->disconnect();
[/quote]
we loop through a database and start a scrape for each row returned

Also is there a way via code or settings that I can tell screen scraper to only perform one scraping session at a time. i.e. to not not start the next scraping session until the next is done