The program you're looking for is AviDemux...
http://avidemux.sourceforge.net/
"Avidemux is a free video editor designed for simple cutting, filtering and encoding tasks"
I've used it myself for splitting a long file into smaller sections, or simply cutting and 'throwing away' some unwanted parts.
Works very well and quickly - for simply cutting into sections, you can just 'copy' the audio and video and set your 'A' and 'B' ie start and stop positions then 'save' the cut video section. Seemed to be that you have to do one section at a time - okay for free and occasional use.
Give it a try.