I just got my new Garmin 430s sounder/GPS for the Advantage. Yes, we're putting a fish finder in an X-Flight 29 The instructions say to download the new software from the Garmin site into an "SD" card. What is an SD card? I have cards for my Kodak camera that say SD on them, are they the same thing? I don't think I have an SD reader/writer on my computer, since I don't remeber ordering one installed when I had it built. What do I need?