The more I read on the subject, the more the aTV seems like an added not needed box by my TV...
If I have a PC or mini hooked up to each TV in the house to stream from my networked HDD or directly from netflix the aTV becomes irrelevant, right?
Pretty much so. If you have a PC or mini, the DRM iTunes store content will play on that device. The only tradeoff in this scenario is UI, as that is done very well on the

TV. If you need a UI that even grandma can use,

TV typically wins that race. If the PC is noisy (fans), that could be another factor. But that's about it.
Some might argue that dedicating a PC to this purposes is overkill. But I would call the 2 Apple TVs I own underkill, in that they are limited in design to only the most modest resolution of HDTV- enough to get away with calling them HD, but it's just barely there. I sure wanted to buy a couple of new 1080p Apple TVs, a feature that many on these very boards have been longing for for a very long time. It took 4 years to get to a completely new generation, and the graphics hardware upgrade went from up to 720p24fps to 720p30fps. Woo hoo! Or is that Boo hoo?
So, if you have a great HDTV capable of better than 720p30fps, another good reason to go with a Mini or PC is so that you have the hardware to really take advantage of your full resolution. I myself am thinking of doing the same, just wishing that the AppleTV UI would become the new "front row" software.
However, I'm also about to replace my HDTV, so I'll probably just let Samsung ship my new (sorta) Apple TV built in. Check out the apps:
http://www.samsung.com/us/appstore And it comes with normal USB ports to which I could connect all of my own media currently streaming to the Apple TV. I'm hoping that Samsung can handle my 1080 Camcorder videos, converted in iMovie to 1080p renders- which, by the way, will play just fine in iTunes (just can't pipe them from there to the HDTV via Apple TV). If so, that's probably my next move. If you don't need a new TV soon though, using a PC will pretty much give you a way to access everything video on the web, far superior to just iTunes, some youtube, netflix, flickr, and internet radio in the new Apple TV.