KeithD

Yeah that's unfortunately way more than I'd be happy to pay for something I use maybe once a week, I appreciate the link though!

It will be fine but I'd personally stick at least one fan in the top to exhaust hot air, otherwise the air just lingers as there is such a small gap to escape from.

The Cryrorig R1 Ultimate/Universal is a good choice for around 60 euros.

Make sure the 24-pin is firmly in (I've had this issue before) as well as the 4/8-pin power for the motherboard. 
 
Which fans are turning on (if any)? Are there any lights turning on?

I have done this before. Windows usually just throws up a "This Windows is not verified" message of something, and you can either choose to ignore it or, better yet, phone up Microsoft and tell them you swapped your motherboard. They'll then okay your account and take off the "unverified" status.
 
If my memory serves me, I can't remember having to re-install anything.

The problem with Newegg is the sales tax and shipping costs afterwards (in pic is a new x61 at $149.99):
 

 
Bringing the total to £126.
 
The x41 looks a very compelling option and I think I will try and get that when it becomes more widely available in the UK. Scan are allowing pre-orders at £80.