Thinktechno.com

Heres a good application for splitting and joining videos.

YAMB Features :
Mux a lot of Audio (aac, mp4, mp3, vorbis…) & Video Files (3gp, mp4, mpeg, vob, ogg, avi…) with subtitles and chapters support.
Split/Join mp4 files.
Extract some tracks from AVI files or raw/mp4/3gp streams, subtitles and chapters.
Have some infos about your files.
Tagging.

NOTE: THis version is also compatible with Vista

You can get the software here

Pranjal