Found by Wizmark!
Ensure you deselect the TV Tuner which will subtract £105.75 from your total.
Evalue 305-D02X26 Cost £643.23 (inc vat&del)
Intel® Viiv Core 2 Duo E6400 Processor (2.13GHz, 1066MHz, 2MB)
English Genuine Windows Vista Home Premium
Premium XPS Service, 2 Year (incl. Gaming and On-Site Support)
Dell 19" Value Flat Panel (E197FP) - UK/Irish
2048MB Dual Channel DDR2 667MHz [2x1024] Memory
320GB (7200rpm) Serial ATA Hard Drive with 8MB DataBurst cache
8X DVD+/-RW Drive
256MB ATI® Radeon® X1300 Pro PCI Express graphics card
Integrated Audio with Dolby Digital 7.1 capability
Dell Black Enhanced USB Multimedia Keyboard - UK/Ire (QWERTY)
Dell 2 Button USB Scroll Optical Mouse - Black
Internal 13-in-1 Media Card Reader
Dell V92 Data-/Fax modem
Microsoft® Works 8 - English
Adobe Reader 7.0.8 - English
There have been quite a few Dell systems this month where you can deselect the TV Tuner to save yourself some money, but Dell have found these and since removed the option.
So better be quick......