PC here too

There is a very good chance that this 3 year old PC will be up to the job, if not then a late 2011 $200 graphics card will sort it out boosting all my older games too where needed.
I'm perfectly aware of that, but see if you can convince my HP Pavilion Slimline 3600z with a mini power source to fully support my 47inch 1080p HDTV without hiccups. 1920x1080 is not something my PC is capable of without toning down certain graphics settings.

True, some of the graphics solutions used by the various manufacturers are below par. That said, there is nothing wrong with tweaking the graphics settings, take Modern Warfare 2 for example, out of the box running on the 360 the game renders at something like 1024x600 and the image is then scaled either internally or by the screen. So, if your 3600z is capable of 1024x600 you're good to go.