Had a PC that was about 10 years old that needed replacing. I was initially going to buy a pre-made but was persuaded to save money and build my own whilst also salvaging whatever I could from the old PC. So after watching a few building guide videos I decided to go for it.
It went pretty well. I took my time with it making sure I didn't screw it up so it did take a few hours. I read that the Cooler Master Evo 212 cpu cooler could be an absolute nightmare to install apart from it sliding around while I was trying to line up the 4 screws, it went pretty smoothly.
The biggest problem I had was with re using my old Windows. First of all because I had to unregister it from the old PC but also because I had to install 3 different versions. First XP, followed by my Windows 7 update disk, then the free Windows 10 update. And because I ran into a few problems (some of them my fault) I had to go through that more than once. If I was to go back and do this build again I would just buy a full copy of Windows 10 and save myself about 2 full days of trouble.
As well as Windows I also salvaged 2 case fans, the CD/DVD player and a 500GB HDD.
The PC is connected to a 42inch HD TV for now so because I'll be playing all my games at 1080p 60fps I didn't need a top of the range graphics card so I chose the MSI GTX 1060 Gaming X. Won't come across too many games that it won't run on Ultra settings at 60fps. Only tested in Doom so far as I've only had the card for a few hours and it ran very nice indeed :)