Mozart there are a number of very good technical reasons for prefering wired:
1. Wireless is a very lossy medium compared to wired with tons of collisions which is pretty much lossless over small household areas. Data speeds are therefore higher in wired but more importantly there is a tightly bounded delay on the data (which is a far more important characteristic). For isochronous data used by games wireless is a much worse idea. This becomes very important for when you are hosting a ten player ridge racer room with everyone chatting away on their headsets. In such situations a wireless setup will have a lot more lag compared with the wired one.
2. This is worsened by the fact that the wireless medium is also being used by tons of other stuff - custom soundtrack streaming from the pc, any wireless remotes/dongles used with mobiles and laptops and the neighbour's wireless which will also cause a bunch of collisions within your own wireless network as they will geographically overlap - if he is torrenting say goodbye to a nice low ping.
3. Wired routers are half the price of wireless ones.
4. Some wireless routers still have security loopholes even when setup correctly to filter by exact MAC address.
So those Gamespotters you came across are actually quite well informed. That's why I went with a wired setup.
Also there is NO NEED to buy the $100 official wireless adapter. Any old cheap one will do for a small fraction of that price. A number of ISPs give them away as well.