After suffering constant slow download speeds (only getting 1.2Mb on an 8Mb DSL connection), I decided to try an alternative way of connecting to my router. I switched off the WiFi and connected a Homeplug Duo kit. I now get download speeds of between 5Mb and 6Mb - a huge improvement. Obviously, the very thick stone walls in my house were having more of a detrimental effect than I realised.
The only criticism I have is that the installation Wizard on the CD only works with Windows. As a Linux user, I found that the instructions were less than straightforward. However, once I figured it out, the system works perfectly.