The new OSX Lion comes as an upgrade from the Apple App Store – not on a DVD. The good news is that once you’ve paid for it once, Â Apple allow you to install it on all the computers you own for free! After you purchase it from the App Store you Â just have to go into the App Store on your other computers and Lion will be there – all paid for and ready to download again!
The Apple page on this is here.
Of course, you need to upgrade all your existing computers to Snow-Leopard first.
The main hitch is that it needs to download lots of files first.
You can make a USB installer and copy it across manually. Here is a way to do thisÂ using the built-in Disk Utility in OS X.