I've got a 500GB Time Capsule with the latest firmware. In AirPort Utility I have the option of 802.11n only or 802.11n compatible with 802.11g/802.11b. Is there a way I can make it 802.11g only? Apart from my iMac (which is wired) I currently have no 802.11n equipment, and apparently enabling both is a small speed decrease.