Hi there,
So me and a few friends are going to throw together a rig for mining some Scrypt based currency. What we mine is undecided yet. Here is what we have picked out as the rig so far, minus the graphics cards:

Intel G1820 2.7ghz Celeron Dual core 1150 CPU - £32.62 @ Scan.co.uk

Corsair CX750M modular 80+ bronze power supply - £73.33 @ Amazon.co.uk

Integral 4gb DDr3-1333 DIMM CL9 RAM module - £23.99 @ Amazon.co.uk

ASRock H81 Pro BTC 1150 Motherboard - £47.75 @ Scan.co.uk

Cooler master Elite 334U Case - £34.06 @ Amazon.co.uk

For the OS, we will be using a Linux distribution, specifically one of the ones designed for Scrypt mining.

This motherboard is meant to be the best for mining, as it has the dual molex power connectors for the PCI-E slots, but is there any point to it? Does it make a difference, by allowing us to not have to use powered risers, or is it a waste? The board is overdue by a few days at Scan, and it is going for over £100 on ebay. Should we be looking at getting a different 6 PCI-E slot board, or is it worth us getting this one for running up to 6 cards?

Next, I've heard that it doesn't matter about CPU at all, so is the one i've picked fine? And if we change motherboard, and go for an AMD system, could we go as cheap as possible and get a single core AMD sempron 145? £28 @ Amazon

If we don't get this motherboard, is there any others in the same price range that you would recommend?

Also if we do get this motherboard, we won't be getting that case as the motherboard only has 1 X16 slot, and the X1 slots aren't open ended. We will build a crate to hold they system.

For risers, is there a particular place we should get them from? I've seen this one:

http://www.moddiy.com/products/PCI%252dExpress-PCI%252dE-1X-to-16X-Riser-Card-Flexible-Ribbon-Extender-Cable-w%7B47%7DMolex-%252b-Solid-Capacitor.html?gclid=CNqduOmal7wCFZRr7Aod4EQAtQ

is it any good? Where can I get reliable, longer ones? And what about unpowered ones, if i don't need them to be powered?

Is the RAM overkill? We'll be running Linux. Shall i just go with a cheaper 2gb stick?

Finally, the video card. We've spotted 2 XFX DD 7970's on ebay at £210 each. 7950's of various brands and coolers go for about £10-£20 less. Should we buy those cards?

Thanks so much for all the help.