This is what is basically a wireless ethernet bridge. If are willing to deal with some configuration quirks go with a standard bridge. Also, get the cheapest one possible because the next generation of consoles will all probably have wifi built into them like revolution. If you are willing to put in some time, you can usually find a wireless bridge at about 30-40 dollars. I bought my netgear ME101 wireless bridge from justdeals.com for 35 dollars shipped. They have them in stock every now and then, and it is a great product. It is, however, 802.11b and not g, but as I said the next generation of consoles will most likely have wireless g built in and internet speeds will not even take advantage of the speeds that G provides until that time comes to pass.
NOTE: If you buy a wireless bridge that does not say that it is xbox approved, be prepared to have all of your IP and DNS settings ready to input because it will not work if you have your xbox set to detect them automatically. Also, if you have an access list on your router, you will need to add the mac addresses of both your console and the bridge into the list. If you chose to go the route of the cheaper adapter, that advice that I just spouted will save you the hours of headache that I had to endure when I set up my xbox for wireless. I do not know anything about setting up a PS2 because I do not have one. Also, if you have multiple ethernet devices that you want to hook up in one room, you can hook up those devices and the bridge to a hub, and it will connect all of them to your wireless network.