There is a cheaper 1300 at £349 but this is the best value having a better screen, larger hard drive and dvdrw.
Do consider the following upgrades, Pentium mobile 1.66Ghz cpu for £23.50 and of course the bigger battery at £11.75.
307-N08136 - £399 delivered or less
Intel® Celeron® M Processor 380 (1.60 GHz, 1MB L2 Cache, 400 MHz FSB)| Genuine Windows® XP Home Edition, SP2 (incl Symantec PC Restore Recovery) | 15.4" Wide Screen WXGA (1280x800) TFT Display | 512MB 533MHz Single Channel DDR2 SDRAM (1x512) | 60GB (5,400rpm) Hard Drive | Fixed Internal 8X DVD+/-RW with Software | For Celeron® M Processors - Dell Wireless 1370 802.11b/g Mini PCI Card | 4 Cell, 29Whr Lithium Ion Primary Battery | Microsoft® Works 8.5 - English | Network Assist - 90 Day Trial
Reduce the warranty to minimum for the above price and buy via Quidco for further cashback savings.