I'm using moviemaker, but just got sony vegas, so I'm learning that. haven't had any issues with merging or converting videos, but I was just like you, didn't know spit about how videos are rendered or edited or anything. Cheap is how to start out though. Something you have or can get for free. Some of these editing programs are incredibly expensive, and you don't want to invest in one until you know what it does, and if you like it.