Is this similiar to what you are using? http://www.primafit.com/equip/commer...enchpress.html
From a general standpoint you will most likely be able to do more on these types of machines than their free weight counterparts. On machines like this you are locked into one range of motion and therefore do not get the benefit of building the stabalizer muscles that you get with a freeweight bench press. Also when you compare how much you do on the machine compared to the free weights, usually the arms on these machines aren't as heavy as a regular free weight barbell (around 45 lbs) so you want to take that into calculation.
My old gym used to have a full line of hammer strength equipment and when it comes to machines, they are pretty good. But for the basic core lifts like benchpress I would recommend doing them off a machine and then using the machine only as a secondary lift. When I switched alot of lifts over to the machines for a month and then went back to free weights, I actually found that I was alot weaker on certian lifts because my stabalizers didn't get a good workout.