I have 3 PC Lan lines plugged into my router which has 4 ports, the 4th port is feeding an 8 port switch where I have 5 more lines and one of those lines I have another 8 port switch (located in my HT center) which feeds all the HT gear. I have had no issues what so ever running this way.
Having written that down, I guess I should try running the HT switch directly off the router just to see if the Xbox works even better this way, not that it has had any problems so it would be hard to verify any benefit.
