There are a few things to check if you are having problems:

1. Make sure you have upgraded the firmware on your Galileo.
   1. In the Arduino IDE Help -> Firmware Update
   2. Follow the directions, it will take a few minutes to finish. 
2. Make sure the SD card is formatted as FAT or FAT32.  
   1. NOTE: SD Formatter should be used to format you SD card
   2. The easiest way to do this on a Windows computer is to open up Windows Explorer (file manager)
   3. right click on the SD card
   4. select Properties
   5. There will be a line that says: "File System"
   6. This should say FAT or FAT32
3. Make sure the unzipped files from the Linux image are in the correct spot:
   1. in the top level of the SD card, the files should be:
      1. boot (a directory)
      2. core-image-minimal-initramfs-clanton.cpio.gz
      3. image-full-clanton.ext3
      4. bzImage
4. When you boot up, you should see a Grub menu, make sure the default is selecting the SD card and not booting from the SPI.
   1. The option to boot from the SD card should contain the phrase: "kernel-MassStorage"  NOT "kernel-SPI"
   2. you can edit the grub.conf file to fix the defaults.
      1. on your SD card:  e:/boot/grub/grub.conf
      2. Open with a text editor and change the default number (or do like I did and remove all the options that are not the SD card)
5. To verify that you have booted with the SD card, you can check to see if the SD card is in the file structure: 
   1. it should be at the path: /media/mmcblk0p1/   (or something similar)