RM Computers are withdrawing from the PC production market, meaning that you won't be able to order one after 30 November 2013.
The University is currently setting up a new range of approved suppliers, which should be active from January 2014. The new supplier agreement will offer a much greater choice of recommended manufacturers.
In the meantime, if your department needs a new computer, IT Services have a limited number of RM machines in storage. ITS are also able to supply loan laptops subject to demand.