Is it sinful for me to download movies from a legitimate web site for my own personal use only?
Are the movies copyrighted? Do you pay for the movies that you are downloading if they are copyrighted? If these movies are copyrighted and you are not paying for them, I would suspect that a law is being broken and a sin has been committed. However, you didn’t really provide enough information to form an opinion. If you, however, are “feeling” concerned about the situation, I would suggest listening to your conscience and avoid doing this in the future. I can say with 100% certainly that it is NOT sinful to abstain from downloading movies. 
Hi Tietjen, thanks for your reply.
As yet, I haven’t downloaded any movies. I’m just browsing for a good legitimate web site where the movies are copyrighted. I have come across one where I would have to pay for the movies which is, of course, what I want but would like to ensure that the movies are copyrighted.
Incidentally, would you know of any such web sites? Thanks again.
Well, I’m not sure if this is what you are looking for but Blockbuster, Amazon.com and Netflix all have movies available for download. I don’t know whether or not Netflix allows you to “buy” the movies but I know that both Blockbuster and Amazon do. Netflix may be a rental resource where you can view as many online movies as you wish for a set monthly fee. Good luck and God bless.