I have built a few PCs from scratch and rebuilt lots into new cases or to clean them out.
The first PC that I built was my main desktop with an Athlon 1400+ CPU(See Specs)
I also built my server out of 2nd hand parts that I bought in a local computer shop. In total the parts only cost me £30 and the nice man in the shop gave me some of the cheaper parts for free including the Socket 370 Celeron CPU (Was going to be £5)
I later upgraded the CPU to a Pentium III which I got in the
same shop for £5. I even got the OS (Windows Server 2003 R2 Standard) for free from Microsoft Dreamspark.
My computing teacher at school even got me and a couple of other people in my class an old computer to take apart and rebuild .etc which is great apart from when you get people who really don't understand what they are doing pulling parts out - one boy even tried to rip out the CPU cooler without undoing the clips
luckily I stopped him.
If anyone has any problems with older internal hardware I am the person to ask.
P.S. I will upload some pics of my PCs ASAP