If you don't have time to learn to setup one of the network rendering systems you can just use the command line version of Blender to render a few frames on each computer and manually queue up more when each computer is done.

http://wiki.blender.org/index.php/Manual/Rendering_From_Command_Line

If you have a little money you should use this service:
http://www.respower.com/

Or if you have time you an learn to setup one of these systems:

http://www.blendernation.com/2006/12/13/more-distributed-rendering-options/