"This Qu'ran has a verse-by-verse Greek translation on the left side with .3 cm Arabic script on the right side of the same page. It is revised by different scholars from Al-Azhar University and Shaykh Jihad Bilal Khalil. The typesetting is done by Syeda Mariyana.
This Qur'an was published under the program of the Saudi government who wanted to translate the Qur'an in many langauges.
There are also a few sites with free downloads, eg. islamway.com
I, myself, don't speak Greek, so can't give you an opinion of the translation. Maybe someone who does will come along later and give you their personal favourite.