To make your Windows start directly without prompting for Boot screen, follow the below steps:
 
1. Click Start
2. Click Control Panel
3. Click System and Security
4. Click System
5. Click Advanced System Settings (On left pane), then click on Advanced tab
6. Under Startup and Recovery, click Settings
7. Now, uncheck "Time to display list of Operating systems" then click on Apply and Ok.
 
For reference, click on the following link:
Change the default operating system for startup (multiboot)
http://windows.microsoft.com/en-US/windows7/Change-the-default-operating-system-for-startup-multiboot