Simple Wireless Camera Needed

Hello, I was researching on how to set up a DIY security camera system for a friend's employer. The employer runs a private music lesson school and is looking to have each room recorded by a camera for liability issues (since children are often in the rooms with their teachers unattended by parents).

I was planning on building a cheap computer myself, install Linux on it, and use ZoneMinder (or similar software) to record a month or so of captured footage.

I am a programmer by trade so I can handle that part myself, but I have no idea what kind of cameras to buy (of which I need seven). I need cameras that broadcast their video wirelessly somehow that can be captured by a computer, so I guess I'm looking for an IP camera?

Also, the IP cameras that I have looked at have more features than I need. I don't need night vision, pan/tilt (they are small rooms), but I do need a microphone.

Does anyone have any camera suggestions for me?

Thanks so much.

Simple Wireless Camera Needed