Installing problem

I reinstalled my whole machine, and when I try to launch blender 2.68 from the folder I extracted the terminal says “blender is not installed please type apt-get install blender to install it” When I do so I get the 2.63 version.
In my previous configuration I could launch the blender straight from the folder in which it was extracted, but not anymore… Any idea?

I found the problem: I used the 64bit application with my 32bit OS. I still wonder why I have 32bit OS.