In addition to the LaCie 5big Office+ that we recently reviewed, Lacie also has the 5big Office. This is a compact server based on Windows Home Server 2011, available at the appealing price of about £345.
Microsoft feels that Windows Home Server is an excellent alternative for a NAS. Opinions on the matter are divided, but if you're looking for a Windows-based network drive and you want to back up Windows computers, then it's an interesting option, even in addition to a NAS. The number of available Home Servers is very limited. If you want to build your own Windows Home Server then you will find out that there aren't many suitable compact chassis available, and the number of energy-efficient motherboards with enough SATA connections is also low.
The LaCie 5big Office is a good alternative, it's a complete Home Server including a 2 TB hard drive at an appealing price, cheaper than the 5big Office+. The features of that model closely resemble this new model, but instead of Home Server 2011 you get Windows Storage Server 2008 R2 Essentials. It's a business version of Home Server suitable for Active Directory that can back up 25 instead of 10 computers. The 5big Office+ also has a more heavy-duty configuration, and a higher price. For a single 2 TB disk you'll pay around £160 more.