You can get RAM cheaper than that. Check these out:
http://www.overclockers.co.uk/showproduct.php?prodid=MY-203-CS&groupid=701&catid=8&subcat=
8 of these @ £23.99 each is only £191.92.
We managed to find a PSU for around £50-60 cheaper than your one.
The money saved there will get you a case or mats to make one. (or just run it naked screwed to a board) and Linux is free!