I’ve heard of a program which can be used to download info for movies like posters and samples
Do you mean this site?
Check out Movie Collector: http://www.collectorz.com/movie/ There are also some freeware programs you may want to look at over here: http://www.snapfiles.com/Freeware/gmm/fwmovieorganizer.html
I use Ant Movie Catalog. It comes with scripts that can automatically get info about movies in your catalog. IIRC it is open source but I know it’s at least free.