I suggest a 2GB GTX 560 TI for your usage. Sorry, but I don't know any links that I could give you if you need it shipped to Greece. Also, if possible, go for an EVGA card... They are usually the best Nvidia cards and have the best warranties.
If you go for the GTX 560 Ti, make sure it is a 2GB model. Most of them are 1GB models, so don't get tricked into buying a 1GB model if 2GB is your target.