Sorry Nearlythere but the

®™ &

®™ smileys are © Copyright 2011 Midlandfire Enterprises Plc.
You owe me £100 everytime you use one of them! Thats £200 please!
On a serious note NT, If you create a presentation (such as a powerpoint) it would normally be deemed to be your intellectual property. Often just by stating that it is "copyright(ed)" somewhere on your presentation and associated handouts might deter others from plagiarising it.
There may be people who ignore that and try to copy your work, subsequently you have to decide on what action you would be willing to take to protect it. Sometimes the threat of legal action against unauthorised copying may be enough, particularly if the "offender" is self employed or part of a small company and thus can't afford the costs of challenging you in court.
In any event you are best advised to consult a lawyer who can advise you further, rather than us PC pilots who can only give you amateurish opinion!