I bought one from Maplins and it transmits a good quality signal but wont go through too many walls.
Downstairs to upstairs through a wooden floor and one wall was fine but two walls and it struggled.
I used a pair for a short while to get tv into the kitchen. The picture was totally wiped out every time the microwave was on. Probably means I'm frying more than me chicken ding!
I use a Philips (I am Dutch, so what can I do...), the sat receiver is in the living room on the ground floor, and the 2nd TV is in our bedroom 2 floors up!! Signal is fantastic !!! Picture quality is perfect ! It only gets bad when someone walks through the signal or uses a mobile phone close to the receiver.
For sure I am also using the Phillips unit, from living room to Conservatory, nice that it has two inputs which means DVD & Satellite can be pumped through to it - though it does suffer from signal loss from people movement and Microwave. This unit also allows additional receivers to be added so I may be able to pump the signal through to the bedroom too for those lazee Winter days.
I actually have to rethink this - I discover that whilst I have enough outputs from my digital tv tuner to feed a transmitter, I don't have any spare inputs on my kitchen tv.
2.4 Ghz is a pretty crowded part of the spectrum. Microwave ovens, video senders, Bluetooth and 802.11b/802.11g wireless networking. Don't expect to have a sender and wireless networking at home without problems.
b.t.w. If you live in a house with thin walls be careful using a video sender for watching porn! This is not, of course, from personal experience it's just a bit of friendly advice