Basically it appears they have also locked it from over the air updates, instead relying on owners using that PC Suite software to do manual updates. I don't know how bothered you are 31t®um but as you are a Mac user it would seem you have no way to update your phone's firmware as they also don't offer mac support!!
Samsung seem to have made a bit of a pig's ear over android with the galaxy:
http://androidforums.com/samsung-i7500/12184-samsung-firmware-updates.html
Basically it appears they have also locked it from over the air updates, instead relying on owners using that PC Suite software to do manual updates. I don't know how bothered you are 31t®um but as you are a Mac user it would seem you have no way to update your phone's firmware as they also don't offer mac support!!