Thank you for your replies.
I checked the i5 and i7 3000 series, and they all have the facility DDR3 1333/1600.
Therefore I will go for an i5 3550 or an i7 3770 which represents a cost increase of 87 euros. Which is the advantage to choice the i7 instead off i5? Maybe i7 is better for the futur Windows 8?
On the other hand, as you recommended, I will choice the P8Z77-V-LE instead off the P8Z77-M.
So the configuration will be: Asus P8Z77-V-LE, with the above i5 or i7 and DDR3 8Gb (2x4)Corsaire Vengeance 1600.
The other pieces of the equipment are nearly similar to your proposed configuration.
I will not use this computer for games but only for Office and mainly for videos made with the soft Pinnacle V14