If anyone is looking for a cheap server machine to stick in a cupboard somewhere the HP ProLiant ML115 is being offered at knock down prices at the moment for some reason. The cheapest I could find with a quick search is:-
http://www.kikatek.com/product_info.php?products_id=40254&source=froogle
£105 for a machine with 1Gb memory, 160Gb hard disk, gigabit ethernet and space for expansion seems pretty good to me.