Wow, what an impressive haul!

What screen size has it got, and what speed is it? Did you get any kb/mouse or other accessories with it?

iMac G4s are nice little computers, we've got some running Leopard pretty decently at the high school.

As for the speakers, you can always just unplug 'em, it should have an internal speaker, and while maybe not the "nicest" option, it should prevent it from buzzing.