Using iMac G4 for our kids (off Ebay?)

Hello,

To start our kids off on the computer, I am condering buying a second hand iMac G4 (? the one with the flat screen on the blob if I'm not mistaken). Not looking to do too much other than let them play with music, alphabet, maths, puzzle and internet things. Will that work? if it is part of our network, can we simply use the older operating software?

Any advise gratefully received!