Is it a good idea to use notes during a presentation/demonstration, such as delivering a PowerPoint presentation of a mobile project in my organization to my colleagues, or does that indicate lack of preparation or self confidence?
Imagine that you gave this talk once, and you realized that there were 4 very important things you wanted to emphasize but forgot.
What would you do to prepare for the next time? Make notes. It might be an index card. Or a piece of paper. It could be the speakers notes from power point.
It showed you prepared.
It showed you had confidence that you understood your limitations.
In and of itself, notes distract from the key points you are trying to present and generally hinder your presentation. They limit the amount of eye contact you make with your audience, enabling their minds to wander. In general, it's better if you don't use them. If you do adequate preparation, you shouldn't need them. The point of a presentation, though, is to communicate ideas. If using notes enable you to be a better communicator, then use them. If they don't, leave 'em at home.
I wonder what choice you're trying to make? Is it "should I practice this one more time to be sure I cover everything I need to without making use of notes?" or "should I just leave my notes behind and pray I don't forget anything?" If it's the second one, keep rehearsing if you can. Whatever minor objection note-consulting might bring up in some people, it pales next to blowing your talk completely, forgetting important points, going twice or half the length you should, talking for 20 minutes to one slide and then discovering the next three slides had all the details you just said, and so on. Be prepared.
Now, if you are prepared but are hoping for the comfort of notes just in case, that's a different story. In general, to be seen looking at your notes might cause some people to think you didn't practice or prepare enough. This isn't necessarily unprofessional - a quick debriefing with my colleagues after a business trip isn't something I rehearse, and a few notes on a piece of paper will ensure I cover all I need to. But if I've been asked to do a presentation, I should be "off book" or at least appear to be.
Power point has a presentation mode that puts your whole slide on one screen (the projector), and the slide, its notes, and thumbnails of upcoming slides on another (your laptop). Glancing here will generally not look like consulting your notes. It's very helpful when I have an eight hour presentation to give for which people paid money. I need to be sure I do things in the right order, and with a large volume of material a few cues are helpful, but I don't want attendees thinking they paid for something that was under-rehearsed and ill-prepared - especially when it's not!
To guauge the tone for the presentation you're worrying about, observe what happens when other people do the same kind of presentation. Do they visibly look at notes? If they do, glance around at the audience and see if anybody reacts at all. Figure out what the norm is for these events.
By the way if you do use separate paper notes, either use a large font and lay the note on the desk or use an index card. An 8.5 x 11 sheet of paper in your hand will dramatically multiply any trembling from nerves, and make people think you are far more nervous than you are. True confidence comes from practice, but the appearance of confidence is something you can slip on just like a suit jacket.
Look at how professional presenters work like politicians and journalists: They will always have at least notes, if not the whole speech printed out before them. Assuming you are not in one of these professions, and that giving presentations is a secondary skill in your work, why should you not use the tolls professionals use?
The least you should do is prepare notes for the slides, except your style is to put everything into the slides, but in this case the question of notes or no notes is not your greatest problem. Having notes prepared, you still can decide to use them or not, but at least you will be better prepared for the presentation from the process of producing them.
I agree with a lot of the other people here. I do want to add though, that interviews is what you can relate this too. In an interview, if you bring notes, they will be happy that you came prepared. It shows responsibility, and that you took the time to do your homework.
It's the same in a meeting - if you show up with notes, then you show the people listening that you have done your homework on the topic.
There are also those who have extremely bad memories, myself included. That isn't our faults! If you do have a bad memory, it's good that you prepare for a meeting properly - it shows you know your stuff; you just need a little help with remembering the important parts.