Im on Post Office and I have an ASUS Router and I can honestly say that when my eldest son is playing on his XBOX, the internet dies a slow and painful death.
Im on a very solid 9.8Meg connection and the internet is absolutely flawless until he starts the XBOX up, and then trying to watch Youtube or catchup on ITV or BBC Player etc, ends up with the bloody circle thingy coming up every few seconds and TV is completely unwatchable.
( What makes this even more irritating is that I have setup a Media Centre PC that uses the bloody arial and so does not require the internet and yet the family still insist on using the bloody ITV Player all the time???? )