I want to have a computer I can use to steam content, play blueray movies etc hooking directly to my plasma. I understand what components I need in general, but is there some kind of remote I could get so I don't have to have an entire keyboard and mouse? Suggestions???
TV tuners can come with remotes. The remote will allow you to control specific software bound functions. The one i linked has a remote designed to control windows media center, which will allow you to perform all the tasks that you have mentioned.
the tuner also comes with IR blasters, meaning you should be able to control auxiliary devices from your computer.