If you need some sound effect (fx) for a presentation, a great, FREE, online resource is soundsnap.com. You do need to register and then 5 downloads per month are free.
There are a lot of sound fx here and the collection seems to be continuously growing. All are free to download and royalty free for use. One of the best features is you can download almost any audio file in either .mp3 or .wav format (I prefer .wav as it can be embedded into PowerPoint).
