Competing computer speakers can be distracting and annoying. A lot has changed. The proper room size and set-up are the two most important issues you can address. I've heard from and seen quite a few computer labs that are set up wrong or in too small a space. The room must be big enough to accomodate your teaching needs.
Larger rooms can handle more sound and allow for greater spacing of equipment.
We used to recommend churches place their computers about four feet apart. Multimedia software, soundtracks, and inexpensive computers have changed all that. There are many 'tricks' to dealing with sound in a computer class. Successful outcomes will depend as much on your knowledge of sound as your experimentation. However, don't go overboard on this by facing the computers away from each other, - because this will cut off what the teachers can see on the two or three computers they are sitting down and working with.