Due to budget constraints I constantly find myself several years behind "current" technology, when it comes to my PC hardware and operating systems. I do, however, make it a point to learn exactly what hardware is required to accomplish a given set of tasks.
Unfortunately, matching system specifications to a given task is often a game. I can't tell you how many times I've been told that I CAN'T accomplish things I regularly do with ease on one of my systems. Often people will speak authoritatively about the absolute need for hardware that is WAY over qualified, and equally over priced for my needs.
With this background I am asking for direct experience with the task I've outlined, to find out what critical specs and PC hardware (CPU type, clock speed, FSB speeds, number of cores, OS, Video card specs) I will need to accomplish one simple thing: Be able to live stream videos, play DVDs, and play various downloaded video/movie files, while driving my TV to its full 1920 x 1080 resolution, and at a reasonable frame rate ( which I assume should be at least 30fps). In addition to the actual specs, it will be a helpful addition to know HOW LONG AGO such specs became pretty common. I.e., if what I need became common place in 2010, that is a helpful reference point.
I probably will want a windows box, if only because I've been intimately acquainted with most MS OS's for many years. I'm also looking for used equipment, because I doubt these tasks really require the latest, greatest machine. Again... not looking for brand recommendations, but the system specifications needed to easilly perform the task.
Note: I have edited both the title and content of this post several times now both for brevity and clarity. For that reason, many comments no longer apply. Also, as the comment thread has already gotten too long, I ask that any further comments or answers at this point be limited to addressing the info I'm seeking.