maps n sd cards

Where do i start? I bought a tomtom 1 from the states, and because i live in Australia i have down-loaded the Aus maps onto a SD card. Whenever i put the SD card in, the tomtom displays the SD card coming out of the tomtom, with a big cross. It wont give me any options. When it is connected to the pc and you go to 'display items' it shows the Aus maps on device. I aint to good at this stuff, please help. Do a need cab files on my SD card? Easy explaination terms, if you can help. Tanx guys

[getsurfers]

Install TomTom home on your PC and use that to load the maps onto the device.