There are a wide variety of tools on the market for presentation preparation. Typically you will want to be able to project your presentation from a computer using a data projector, be able to print it in some form as handouts and possibly put it on the web. Some of the tools have the capability to do the preparation, presenting and web generation, whilst others require external programs to present it, and put it on the web.
Probably the two most commonly employed tools for presentation preparation are Microsoft PowerPoint and LaTeX/Acrobat Reader. The decision is not straightforward, since neither package is a panacea. Consequently, hybrid solutions are starting to appear.
PowerPoint is probably the most straightforward but it does not know how to typeset mathematics properly. Additionally, if you are wise and have prepared your paper using LaTeX you will have your material in TeX form.
If you don't have much mathematics you may want to use PowerPoint. If you have mathematics then either use LaTeX and Acrobat Reader in full screen mode for presenting, or use a TeX plug-in for PowerPoint to correctly layout the mathematics.