After installing Ubuntu 14.04, the default boot entry for Grub is set to "Ubuntu" (the first one in example as below).
Ubuntu (Recovery mode)
Memory test 1
Memory test 2
Windows 7 (loader)
To change the default boot entry to 'Windows 7',
1. Open 'terminal' in Ubuntu
2. Type "sudo gedit /etc/default/grub"
3. Find a line saying 'GRUB_DEFAULT=0'. All the entries in the GRUB menu are zero-indexed.
i.e., the very first entry is indexed as '0' and the last one is indexed as 'n-1'.
4. Because 'Windows 7' is listed at 5th position, it has index '4'.
Edit the line to 'GRUB_DEFAULT=4', and save the file.
5. To apply the changes, type "sudo update-grub" in terminal