Presumably the implied point is that this list is really for a stonking PC rather than a "family server" - although it probably has the ability to be both. Implicit in the term "server" is really that it is a host for centralised resources such as disk space, email management and the like - IMHO. The machine described in this list has a hugely power processor, graphics card, PSU (needed for the former two items possibly - but not for more lightweight server like system). You could arguably build a very effective family server for 25% of the price.
R. Marshall and A. L. Harvey are correct. You really don't need this for a family home server. The best thing for a home server would be to run FreeNAS. It can provide SMB, UPnP, AFL, an inbuilt torrent app, everything a family could need from a server. The only benefit to running Windows would be for Media Centre Extender on the 360 (not worth the £168 in my opinion, since the 360 can read from UPnP shares), or if you're going to be running games and other apps, in which case we're talking about a proper family PC, not a server.