Can someone explain to me the difference between SD and SDIO. I'm looking at getting a PDA soon. I'm not quite sure of how important a feature this is. I'm interested in getting a Toshiba Bluetooth SDIO card for the SD slot. Toshiba's specs say that this card is compatible with any PDA with an SD slot. Is this true? Or, are they referring to any PDA with an SDIO slot?