Dell have very recently introduced their new range of Dimension desktop PC's the 9200 series. These come in 2 flavours, either dual core or the new core 2 duo. This deal is for the dual core ones and I will post another for core 2 duo systems.
This first one is not the lowest price available, but I think its slightly better value so I will list it first.
**Edit: Now 1gig of ram for this price NOT 2 gig
307-D09925u - £599 delivered or less
Intel® Pentium® D 820 Processor (2.80GHz, 2 x1MB cache, 800MHz FSB)
Genuine Windows® XP Home Edition (Does not include Operating System Re-installation CD)
**2048MB Dual Channel DDR2 533MHz [2x1024] Memory
250GB (7200rpm) Serial ATA Hard Drive with 8MB DataBurst cache
16X DVD+/-RW Drive
256MB ATI Radeon® X1300 Pro PCI Express graphics card
Dell 19" Value Flat Panel (E196FP)
Integrated Sound Blaster Audigy ADVANCED HD Audio Software
Dell 2 Button USB Scroll Optical Mouse - Black
Microsoft® Works 8 - English
Remember to reduce the warranty to minimum and buy via Quidco for further savings.