Initial user reports on AccellerateYourMac are good on Apple's new Airport Express with AirTunes. If you haven't heard of this, Apple's released a $129 802.11g (WiFi) gateway that allows you to play your iTunes through speakers attached to the device. Great if you don't have a wireless network already or if you are looking at extending the network.
This looks to be another fine product coming out of Phil's group at Apple. Kudos and good luck, Phil.