Just to say that despite the fantastic deals that Dell are banging out recently, you should still get on the phone to their sales people.
I've bought 3 machines from them for friends recently including the fab £328 machine and a couple of Laptops. The last laptop also included the 5% code posted here
Anyway, on all of the deals I've ended up getting another tenner off by ringing them up and negotiating over the on-screen price.
Start off looking for another £30 (or free delivery if not already included) and get haggling. Tell them you are ready to buy right now, and keep pushing. You'll get your tenner.