Also have a look at:-http://www.pcspecialist.co.uk/https://www.pcspecialist.co.uk/forums/f ... p?32-Linux
I have a desktop macghine from them with Xubuntu running brilliantly, though it also manages Ubuntu with no difficulty; I just don't like the unity desktop, hence Xubuntu.
I came with no OS (actually with Win 7 for testing purposes, but no licence for that included) so saved £80 on that. It's an Intel i5-3570K using the on board graphics, with 1TB HDD and 8GB ram, so no slouch, and does all I ask of it very fast. PCS are very good to work with and they allow you to customise the specs of your machine on their web-site.
Highly recommended! Have a good look at their site.