Dragon Naturally Speaking is an excellent Voice Recognition System supplied by Nuance Communications, Inc.

Communicate more easily

A comparison chart for the Dragon packages is available here.

Voice Recognition

For use on a PC the main choices would be “Microsoft Speech Recognition” which is included free in Windows 10, 8, 7 and Vista or “Dragon Naturally Speaking”, see below.
The Microsoft option is quite workable and provides reasonable access to system operation for just the cost of a headset.  However there are some features that Dragon has that may make it worth the added cost.

Dragon Naturally Speaking

Dragon comes in various forms: Dragon home (£40), Dragon premium (£84), Dragon Professional/Dragon Legal/Dragon Medical  (£500)
(These prices are approximate lowest prices as at beginning 2014)

From the point of view of general usage I would recommend Dragon premium.  This includes features such as Text-and-Graphics Custom Commands which allows you to have specific blocks of text or images inserted into your document with a defined command and support for Excel and Powerpoint.

If the package is to be used in a business environment the Access to Work scheme may be used to fund the necessary equipment and the Professional, Legal or Medical packages may be needed.  If the user may log on from different workstations one of the Professional packages will certainly be needed as they support the facility of storing the user profile on the server for access from any workstation.

If you are intending to use voice recognition on a PC you should bear in mind that it is a fairly resource hungry activity and I would recommend, as do Nuance, the following System Requirements: not less than 2 GB of memory and a dual core processor that runs at not less than 2 GHz with 2 MB of L2 cache. Check on www.nuance.co.uk for more precise information.