Check out Sound Bible for your PowerPoint decks
Sound Bible has some useful, free music and sound effects that can jazz up a PowerPoint presentation.
There’s a collection of free audio clips (various rights limitations) from here. In WAV or MP3 format, both compatible with PowerPoint.

Many of the text labels are deliberatly bland to avoid copyright disputes. For example Cowboy Theme is instantly recognizable to most people.
A few sounds that caught our ear …
Happy Birthday To You not copyrighted in US or EU
Sports Crowd 40 seconds of a cheering crowd, can be shortened.
Cowboy Theme famous theme, use as an intro?
Count Off – drummer counting as high as he can <g>
Sound Recording Copyright ℗ symbol in Word, Excel, PowerPoint and Outlook
Add genuine BBC Sound Effects to PowerPoint
Law & Order titles and sound in PowerPoint and Office