Mate you can get the same setup with a much better motherboard and ram for £100 from Ebuyer delivered direct to your door.
That ECS board is old school, get the slightly bigger brother I pointerd to, with the e2140 processor (same as you have listed from your local supplier), and with a full 1gb of DDRII 800mhz delivered all for just over £100.
But personally if you would like to overclock then you can not touch the ECS at all, and trust me, we will tell you how to overclock it just by pressing a few buttons on your keyboard, and to do this you overclock you will need an Intel chipset.
Obviously every board has it's limitations but I would spend your £100 with advice from us on here.
For £100 I would go for:
This motheboard:
http://www.ebuyer.com/product/136368/show_product_specifications
£36
It has the Intel chipset which you would need for any chance of an overclock with that processor. It also has a much better built in sound (7.1) than the ECS.
Processor:
http://www.ebuyer.com/product/127249
£41
Dual Core using Core 2 Duo technology and has great clocking possibilities if needed, a little less cache than Core 2 but that has nothing to do with what you need, in fact this is the best you can get for the price for what you need. It will still cripple any Celeron/Athlon you have posted and will benefit you when burning DVD's due to it having 2 cores.
Ram:
http://www.ebuyer.com/product/91121
£12.99
Kingston 667mhz DDRII 1GB module (1 stick)
Case:
http://www.ebuyer.com/search/?strSe...&intCatID=23&intSubcatUID=418&bolShowAll=true
A massive choice of cases from the above link, loads of cases with bult in PSU's for less then £20, some are less than £15 with 400W psu, and trust me for what you are using your PC for a generic 350W/400W PSU will be perfect, so just add another £15 to the total.
We are talking £105 for the above, all from one company delivered to your door within 5 working days.
Much better than you posted mate, you have a better motherboard, a full 1gb of ram with lifetime warranty over the 512 you posted and a varied choice of cases.
I think a fair few would agree the above is what you need for your £100.
P.S.
Any Dominoe players on here, if so P.M. me.