Beginners should choose the default installation for any of them.

Boot Think 2 update:

1. Support files are installed under Windows including support for Windows 7

2. In support of Windows under the direct replacement / Darwin / System / Library / Extentions.mkext drive buffer

3. More accurate identification of Windows systems (XP, Vista, Windows 7)

4. Support for any NTFS partition directly from Windows systems to guide

5. Ubutuntu enhance the grub on the Linux system boot, etc.

6. Set the default boot partition, and the countdown

Upgrade 2:

1. Installed in windows

2. Update / Darwin / System / Library / Extentions.mkext under windows

3. More accurate identification of Windows systems

4. Boot windows from any NTFS partition

5. Better support for the grub

6. Setup default boot partition and countdown