Dont bother with the speedbooster just get the top one, ive got it and it works brilliantly. 5/5 reception all the time :) .
If you're also after a wireless network card for your pc, id recommend this one...
http://www.ebuyer.com/customer/products/in...oduct_uid=50127
Oh yeah one more thing! If when you get it all set up you find the xbox cant detect the network, go into the router settings (http://192.168.1.1) and change the wireless output to 'Both G and B' instead of 'G only'. I had that problem and it took me all day to work out what it was :P