You're right; originally I had planned on building one, back then was for living-room htpc, needed to be sff to fit, ended up getting a used optiplex 3010 w' windows 10 for like $75 and it's worked fine for what I use it for--streaming video and general browsing. That was many years ago and haven't really thought much about hardware until now, and yeah, I know the parts are substandard, lots of bottlenecks etc so will build one this time (thanks for the heads up, I now know that I don't have to pay so much for windows.)
That's a great setup, definitely more than I need but for the price-point super. I'd be a bit concerned with how much power that would take up as I usually do very low resource stuff on my computer, for example this new setup is going to be for another room, I've been using a 17" hp/compaq nx9600 laptop and for the most part can still use it; but with a pentium and xp it's time to upgrade. The only things I do that might take more resources is some audio programs like fl studio and my child while can play some steam games like goat simulator out here on the optiplex it glitches when going into space and other games need dedicated graphics so it'll be good for that. I wonder if I should get a sound card as fl studio asks for one--I use the generic ASIO4ALL driver which seems to work alright. I appreciate the advice, got me back on track.