Beersmith has the numbers already set for the malts. I don't have it infront of me, but I think there is a 'malt' tab where you can call that up. I've seen DME and LME values very about 2 points, which doesn't sound like much, but can make the OG's off by about 3 points in a beer with 6lb of malt extract. I'm not sure where Brad got the numbers, but they are not unusual.
Anyhow, when you type in "Pale LME" and then put in the lb, it should list how much points are going in, or the effect on OG.
OH one other thing, Beer smith has a whole bit on your equipement, so it might be working as if you are doing a grain and not an extract, and working with a 1 gallon boil off and all that. That will really change numbers. Check to be sure your final volumes are correct - I assume 5 gallons.