Sabriena's sister Shaina has been dealing with an old (Vista-era) PC since forever... while we were visiting, I cleaned all the (significant) dust out, reinstalled a modern-ish OS (Windows 8.1, unfortunately) and installed a discrete GPU (a ~5 year old, low end nVidia). It worked for things like Team Fortress 2, but was still rather painful, so she resolved to use some of their tax refund to get a new one.
Her kneejerk reaction was to simply go and buy whatever shiny piece of shit Walmart was selling, like we always did (every time I had the money for a new machine it was, conveniently, an emergency, so I haven't built a PC in nearly 10 years). Sabriena and I both basically told her that if she were to build a PC she'd come away with a significantly better machine for the same money, and after umming and ahhing for a while she figued out a budget of about five hundred bucks. I promised to walk her through assembling it via Google Hangouts.
We headed on over to one of my favourite websites, LogicalIncrements, to see where that would get her. We settled on a ~$420 build, to leave room for any unforseen extras. She fucked around and procrastinated with the shopping list I left her until the G4560 CPU was sold out, so she bought a G4600 instead. We bought a few other extras, like a DisplayPort to VGA-DSUB adaptor, because her old monitor was VGA-only and a new one was outside of her budget. Also, an anti-static strap and some spare thermal compound.
Things started arriving Friday (AEDT), but not all of it. We did manage to get the power supply and the hard disk installed in the case, which worked out rather well. She wasn't near as useless as I figured she'd be (honestly, someone younger than me being so useless that they don't even clean the dust out of their PC for five years is simply unacceptable to me) and I feel like her confidence grew quite a bit.
Saturday the last component (the CPU) arrived, so we went the rest of the way. There was a couple of minor moments of confusion (we hooked the power switch wire up to the wrong place - my fault - so nothing happened when we tried to boot it, and also her GPU apparently doesn't have an external power supply, which I thought was weird).
I had her burn another copy of Windows 8.1 to a USB stick using the old machine, but then when we tried to install it, it didn't work. We hooked it up to her hold hard disk, updated some drivers, and she's been playing it since. For such a budget build, it performs quite well - the new Kaby Lake stuff is great. She gets a solid 250~300FPS on Team Fortress 2, and is able to play The Sims 4. So far temperatures are staying well within reasonable (30~40C), though it is still winter there. She's got plenty of room to upgrade too - the motherboard and powersupply will happily support significantly faster CPU and GPU, and she can drop more RAM in (currently using only a single 8GB stick) without throwing any away, and she can also drop an SSD in. Heaps of room for improvement as finances allow without wasting much.
Shaina seems really happy with it. We still need to work out installing the OS on the new hard disk, because I think it'll be faster, and she also went ahead and bought an optical drive, after formerly deciding to forgo it then realizing she burns CDs sometimes for their older car... an optical drive is cheap these days, less than twenty bucks.
I'm hoping that the process of building her own PC will make her a little more inclined to keep up on the maintenance of it.