configuring windows boot loader for dual boot

Depending on what version of MS your running, the windows partition will have to be the main partition (c.

How is your hard drive currently configured? Do you have a single drive with different partitions or do you have multiple hard drives in the box?

For dual boot screen, all you have to do is:-
Insert the DVD of operating system & then it will automatically search last version of windows installed in your PC. After that it will show you active partition of you computer, after that you have to cancel that window & ask for new installation. Select the secondary partition for installation otherwise you may lost your previous OS.

bcdedit is the way to edit the Windows boot loader.