The PowerEdge has a choice of Intel Pentium or Xeon processors, is expandable up to 32GB RAM, has four 3.5" drive bays plus can accommodate another two 2.5" drives via an expansion kit.
Dell are aiming this server at the small office and the home-based office. No operating system is supplied, but a suitable offering would be Windows Server 2012 R2 Essentials. One shortcoming of the T20 is that it only has software-based RAID, which we would not recommend (see The World of Fake RAID).
A number of pre-canned configurations are available from the Dell website. At the time of writing, a Xeon-based model with 2 x 1 TB SATA drives, 8GB RAM and a basic one year warranty costs £528 + VAT. Allow for a copy of Windows Server 2012 R2 Essentials and some form of backup drive and you are looking at over £1000 for a working system. Whilst not outrageous, a Seagate Business NAS with 4TB storage and a backup drive is currently available (15/11/2013) from ebuyer for less than £200 and would provide sufficient functionality for many (see http://www.ebuyer.com/491331-seagate-4tb-business-storage-2-bay-nas-external-hdd-black-stbn4000200).