ubergeeknz: The major problem where I am is our neighbours are very close, so 2.4Ghz interference is massive. Also where my router is situated is near one end of the house. So a 2nd AP situated near the middle of the house with 5Ghz or maybe dual band on a different channel should do the job (it's a small house)
Good luck, if you haven't already see if you can find some free or cheap wireless monitoring software. I use Wifi Explorer on my mac, it shows all of the nearby wireless networks and what channel they are using, is helpful when trying to find a channel without saturation With 2.4Ghz however your only real options are channels 1 , 6 and 11