Are you sure it's ES and not ES10 (against a 10 only, not against an ace)? There is about a 0.5% difference.
As far as your betting strategy, with such a small bankroll you aren't going to make a huge score so you probably want to milk the game...unless you expect someone else to burn it. Find out what the casino's choke point is. If you can still earn a decent wage then try to stay under it for as long as you can. You can always become more aggressive once you build up your bankroll and/or start getting heat.
-Sonny-
