Blender 2.7x should run out of the box, without installation procedure. To use Blender, just unpack the archive you find in the download section and start Blender!
(Note: These requirements are valid for the upcoming Blender 2.77 and the Buildbot. Blender 2.76 still supports Windows XP and OpenGL 1.4 graphics cards.)
Blender should run on all systems that support OpenGL 2.1 and above.
Blender is available for Windows Vista and above, Mac OSX 10.6 and above, and Linux. Blender uses OpenGL for drawing the entire interface.
The Blender developer team welcomes all efforts to bypass issues with specific configurations, but we can only officially support the platforms that are in use by active developers. Check the wiki for a list of supported platforms.