In reply to Mr Fuller:
re movie maker (i'm asking these questions because i don't have it installed, so bare with me)
can you import the files into movie maker and do the editing you want to do, but when you export the finished result (ie rendering out the final result) you can't save that as a .mov?
it's quite normal in the world of video editing to either transcode the files from your camera to a less compressed format before you start editing, but you don't want to do that... however there's noting to stop you doing that transcode on your output... ie putting a .mov into the video editor, but talking an .mp4 or .avi out. (for example, i'm editing a flashmob video just now that has footage from a gopro, a sony a6000 and a samsung nx "something" camera, each one has recorded in a different format, doesn't make any difference when laying the files out on a timeline. as long as your editor can read the files it's fine
you said you want something that's not CPU intensive because you have a slow computer.
problem is, video editing is a CPU/GPU intensive task, but if you can leave the machine running while it renders the output it doesn't really matter too much, I've left a machine running overnight in the past to let it finish an output.