From a fellow eMac user, yes, any USB k/b, no need for drivers, just a simple detection process to go through for non-Apple k/b's. I've used generic Win k/b's for over three years and much prefer them - and they're much cheaper than Apple brand.
Three differences in particular you should keep in mind:
1. Cmd (Apple) = Windows key
2. Option = Alt
3. Eject optical disk (if applicable) = f12 (hold)
You'll get used to those changes very quickly. Things like Ctrl, Esc. Shift, Tab etc are just the same.