I recently managed to pick up an original MacBook Air from 2008 in fantastic condition, it even came with it’s original charger and the original (optional) USB SuperDrive. This one is original 1,1 version so it has the 80GB 4200rpm hard drive that could be found in iPods at the same time!
I put a clean install of Leopard (10.5) on it as this is what would have originally shipped with it. For a 1.6Ghz Core 2 Duo with 2GB of RAM and the 4200rpm iPod drive, it’s actually pretty quick!