What hardware would you recommend for Linux?

Ok, this is a self answering question in response to a number of queries recently.

1. Motherboard, ASUS M4AXXXX series, I've tried a number of variants and all seem to work Ok.
   (this is the AM3 socket board with DDR3 support)
   ~ £50-£60
   
2. CPU, AMD Phenom II X4 (3.2GHz)
   Don't be tempted by the 3.4GHz, they seem to have acquired a reputation for overheating.
   ~ £120
3. Disks, Samsung Spinpoint F1, 1Tb @ 7200rpm
   There are many choices here, this model is relatively low power, low noise and performs well.
   ~ £50-£60.
4. Memory, Corsair DDR3 (1600) , 4G (2x2)
   The boards have 4 slots so you can double this if you want more RAM.
   ~ £80.
5. Graphics card of your choice, I'd recommend Nvidia but specs and prices vary wildly so it really comes down to what you want to do, how much you want to spend etc .. or you could opt for one of the ASUS motherboards with on-board Graphics .. a "good" Nvidia card will probably cost you ~£100.
   ~ 'Acceptable' performance from ~ £40.
   [a quad head card for driving 4 monitors such as the Nvidia Quadro will cost you about £300]
   

Stick this little lot in a case with a DVD drive and it'll blow your socks off, I would estimate around 5x quicker than your average "off the shelf" £380 PC ...

[be warned:: use "too" cheap a graphics card and your user interface will suffer]