When I first got broadband in my flat, I bought a BT Voyager 2100 router to deal with all of my network (wireless and wired) and up until about 9 months ago this did the trick quite well. However, with the large amount of media streaming that I now do, I had to find a cheap solution that could 'boost' my network - meet the 'Zyxel Dimension GS-105B'
--What this is...--
This is a WIRED gigabit switch, it connects to your existing network through an ethernet port and extends it by supplying 4 extra ports at gigabit speed.
--What this isn't--
This does not have wireless, so you wont speed up any wireless connections that you have in your house. Also, it is not a 'managed' switch, so you cant do any really geeky things with it, its just a simple plug and play thing. Finally - it is not a modem - it doesn't connect to your phone line or cable to give you internet at all.
So this is a gigabit switch - meaning that you can plug it into your existing network system and it will extend it by giving you more gigabit ethernet ports to play with (in this case the number is 4). It is a very small box, and is very straight forward to set up, connect up the power, fire a CAT5 cable between it and your existing network and then any more into anything else that you need hooked up. There are 5 lights on the front of the box that light up dependant on what are connected that make it easy to tell what is hooked up.
So firstly, I have the gigabit switch connected up to my existing broadband router through one of the ethernet ports. The switch is then connected to a media server (which hosts all of my tv shows/movies), a gaming PC (in a different room but used sometimes for watching movies), an XBox (used to watch a lot of movies) and finally a network printer (this could probably be done on the megabit part of the network, but just incase of big files I used the gigabit.
This may seem a bit complicated for a setup, but if you are wanting to stream any sort of high bandwidth media content throughout your house then this type of setup is really what you need. For me, the change from megabit ethernet to gigabit ethernet was huge and really made a difference to what I could do with all my computers.