I found this deal on Hotdeals, seems pretty good.. If I had the spare cash, I'd buy one..
Inspiron Desktop 546 MT Order - UK (Evalue Code D004604)
Price before discount is £359 but use discount code R08PMW7N?FVGDL at checkout and get this for £323.09 including vat & shipping
Genuine Windows Vista® Home Premium SP1 (64 Bit) - English
AMD Phenom X4 9750 (2.40GHz, 512kx4)
Microsoft® Works 9.0 - English
1 Year Limited Warranty - Collect & Return
8192MB 800MHz Dual Channel DDR2 SDRAM [4x2048]
1TB (7200rpm) SATA Hard Drive
256MB ATI® Radeon HD 3650 graphics card
DVD +/- RW Drive (read/write CD & DVD)
Dell USB Entry Keyboard - UK/Irish (QWERTY)
Dell 2 Button USB Scroll Optical Mouse - Black
19-in-1 Media Card reader
Integrated 7.1 Channel High Definition Audio
DataSafe Online Backup 2GB 1 year
1Yr Limited Warranty - Collect & Return
Piano Black
Very decent spec, not sure why you would need 8GB of RAM though
Link To Dell Site