You will see the Grub menu when your ubuntu system boots,and the only issue is that the default timeout in 10 seconds.This brief tutorial will tell you how to change the default timeout.
Open a terminal window and type :
sudo gedit /boot/grub/menu.lst
At the next window find the section looks like this:
## timeout sec # Set a timeout, in SEC seconds, before automatically booting the default entry # (normally the first entry defined). timeout 10
Change the number after “timeout” that is in seconds,then save the file.you will have that time to choose the menu item you want when you reboot.