Hat is the latest version I can use on a 2006 white MacBook Core2 Duo?

After a long time away I thought I would return to Ubuntu. I have an old 2006 white Macbook maxed out at 2Gb of RAM and have installed 14.04 server on it. I wondered how far I can upgrade, and whether it will run the Lubuntu desktop?

Part of the reason for 14.04 server is that I could find a mac iso for it, and can't get any more recent iso to boot in the MacBook.

Any thought gratefully received.