On this page (in french) you can download many books, esp dictionaries, on greek : http://www.areopage.net/a34.html.
I particularly recommend this greek-french dictionary : Anatole Bailly, Abrégé du dictionnaire grec français, which is the reference dictionary here in France. It's 900 pages and about 35 mega in PDF format. This dictionary is now in the public domain, so, feel free to download it here : http://fdier.ifrance.com/Bailly.pdf. You can also read it online here : http://home.tiscali.be/tabularium/bailly/index.html.
Best wishes for the new year !