If you were buying a new system, tell us everything you would want on your system:
Which brand of processor and speed and why.
How much ram and why.
Type of hard drive and why.
Which brand name on the system since brand name affects which motherboard you may get inside. Which brands have an Intel motherboard, or Nvidia. Which brands will give you a generic motherboard with questionable lifespan.
All in one or not, and why, and what is not included if you do not get an "all in one."
Exclude any warranty you'd get as an add-on, monitor, mouse, keyboard, O/S,