mounting 120mm fan

[Mr_Happy]

Ill soon be starting a mod project on my case side panel and im going to mount a 120mm fan in the middle. What I want to know is how much space do I need to have for the screw mounts?:?

http://pic.piczo.com/img/i23210006_90092_3.jpg

Thats what I want to do with the case, the middle will have the 120mm fan mounted & Ill mount acrylic in the windows.

Any and all help will greatly help.

Thanks MrHappy

[Malatory]

basic specs of a 120mm fan is.
center screw hole to center screw hole is 4 & 1/8 inches
top to botton edge of the fan is 4 & 3/4 "
Center Piece is 2" Dia.
Fan Dia is 4 & 1/2 inches.