I'm just bitter because in my first year I did 90% of the work (as in, picked the topic, wrote the entire presentation and designed the poster) because no-one else in the group could be bothered. So I gave them all a 1st despite me having a fulltime job and the rest of the group not.

So personally? I'd make them do presentations but would insist they did it individually. Then you know they've done the work.