Remember to reduce the warranty to minimum where applicable and take all Dell deals right through to checkout for final pricing.
Trying to dig out the cheapest desktop base at Dell, this is £258 but is a bit low spec so I upgrades some bits.
Upgrade the OS, ram and hard drive as below for £269 delivered. If you need a dvdrw thats an upgrade too but your better off leaving that and buying your own elseware.
305-D072204 Small Business site - Best price £269.10 Delivered.
Dell Vostro 220 MT (D072204)
Vostro 220 MT Standard Base Mini Tower Chassis
Intel Pentium Dual-Core E5200 processor (2.5GHz, 800MHz, 2MB cache)
Genuine Windows Vista® Home Premium with Service Pack 1, 32-bit - English
2048MB 800MHz Dual Channel DDR2 SDRAM [2x1024]
250GB (7200rpm) Serial ATA Hard Drive with 8MB DataBurst cache
Integrated Intel Graphic Media Accelerator X4500
Display Not Included
Integrated 5.1 Channel Audio HD
Dell Entry Quietkey USB Keyboard - UK/Irish (QWERTY)
Dell 2 Button USB Optical Mouse
Norton Internet Security 2009 - 15 Month Protection - English
1Yr Collect & Return Warranty - No Upgrade Selected
16x DVD-ROM Drive