i'm upgrading to leopard this week. i have a MBP and a PC on the same network, and i want the MBP to backup wirelessly. if i get an airport express and a USB hard drive, can i: - add it to my existing wireless network as an access point - plug in my USB hard drive as an "airdisk" that both the MBP and the PC can access to backup & stream movies/music over the network? ???