Obligated means you have no choice. There could be reasons you are "obligated" to finish your work by the end of the day, but it sounds a little too strong. "I'm obligated to attend this boring work conference this weekend." sounds more appropriate because it's something you don't normally have to do and you really don't want to. Obligated has a very strong negative connotation.
Obliged, on the other hand, can mean the same as obligated sometimes. However, it can also be a positive thing. In fact, where I'm from in the US, it's common to say, "Much obliged." instead of saying, "Thank you." To me, obliged is more often positive, and it means you are doing someone a favor.