ADVENT QT5500 15.4" INTEL CORE 2 DUO T5500 PROCESSOR 1.73GHz LAPTOP is available @ PCWorld for £499.99 (collect @ store).
Credit to exit75 for pointing this in HP laptop thread. Plenty in stock @ London. Currently OOS at Dixons & Currys which could have been a better option as there is a further saving of £25-£30.
Features : Intel Core 2 Duo T5500 Processor 1.73GHz | 667MHz FSB | 2MB Cache | 1024MB RAM | 80GB Hard Drive | DVD ReWriter Drive | 15.4" Widescreen Display | Microsoft Windows Vista Home Premium | 128MB Intel UMA 950 Shared Graphics | 1 Year Free Warranty