You don't say what format the source is. Or how you want to save it. So I'll omit advanced editors.
Here are some MPEG editors:
Here are some AVI editors:
One of my favorites is VirtualDubMPEG2, which can import both AVIs (so long as you have the necessary codecs) and MPEGs, although it cannot save as MPEG. (Yeah, I know about the ympeg plugin). As a rule, it's easier to edit video when in an AVI wrapper, and all filters, resizing, recompression, etc., are quicker. On the tool pages above, make sure you check out available guides, you'll need them if this is your first venture into editing. Good luck.