Mini tower case.
350w generic PSU
Asus M2N-MX motherboard
AMD Sempron 3200+ CPU with a clock speed of 1.8 Ghz
4 GB DDR2 RAM
Main HDD - 111 GB (SATA interface)
Secondary HDD - 80 GB (SATA interface)
External HDD - 1 TB (SATA interface in a USB 2.0 enclosure)
OS - Windows 8.1 64-bit
Graphics - NVIDIA GE Force 210 1GB
Optical drive - LG CD/DVD rewriter (IDE interface)
For the choice of CPU, I've decided to stick with AMD only because you get more for your money. It will be a mixture of new and secondhand components. I will try to source as many of the new components from the same supplier as possible to avoid incompatibilities. I got this from one of my brothers for free and it has 3 fans inside the case.

The first part I've bought is this 850W PSU which is more than enough for my needs. It cost me just under £30.

I'm trying to future proof this PC as much as possible so I'm going for the latest AMD CPU socket (which is AM3+) and can take DDR3 RAM. The power supply, motherboard, CPU and RAM are at the heart of this system and will be sourced brand new from the same supplier.
One component which can be sourced secondhand is the graphics card. I've been researching benchmarks of various cards and comparing a few. I had budgeted about £60 for a brand new one but with a secondhand one, I can get more for my money so I've won a decent one on ebay. I just need to fit a new optical drive and I'll carry my main HDD over (this will be eventually replaced with an SSD) and the 1 TB HDD in my external HDD enclosure will be my secondary HDD. I will sell on my old PC as the remaining HDD has Windows XP installed on it. I reckon that it will cost me just over £400 once I've done.
This will be the final spec:
Midi tower case
850W PSU
MSI 760GA-P43 (FX) motherboard
AMD FX-4350 CPU - this is the Bulldozer one which is clocked at 4.2 Ghz and is Quad core.
8 GB DDR3 RAM
Main HDD - 250 GB SSD
Secondary HDD -1TB HDD
AMD Radeon HD6950 2 GB graphics card (just won this on ebay)
OS - Windows 8.1 64-bit.
I will be carrying over my keyboard, mouse and 24" widescreen monitor.
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