I've gone for the below at £159, seems to be reasonably good spec for the price, also comes with a COA to may have a legitimate server OS to play with also, although not too bothered either way as can download Eval versions:
http://www.ebay.co.uk/itm/390867056128DELL POWEREDGE 2950 II 2U SERVER
*2 x 2.66GHZ QUAD CORE XEON X5355 CPU's
* 64BIT CPU's
* 8 GB RAM FBDIMM'S
* 4 X 73GB 15k 3.5" SAS HDD's FITTED
* WINDOWS 2003 R2 SVR ENT EDITION COA ON CASE (NOT INSTALLED OR SOFTWARE PROVIDED)
* SPACE FOR ANOTHER 2 HDD'S
* NO EXTRA CADDIES OR BLANKS PROVIDED
* PERC 5/i RAID CONTROLLER
* DELL REMOTE ACCESS CONTROLLER (DRAC)
* ONBOARD GRAPHICS
* 2 x 10/100/1000 GIGABIT PORTS
* 1 x SERIAL PORT
* 4 x USB PORTS
* 2x PSU's
* DVDROM
* BLUE FRONT BEZEL