In short, the answer is yes. The GRUB bootloader will boot any operating system you like. Debian isn't as newbie friendly as other similar Debian based distros such as Ubuntu at doing this, but please have a look at Chapter 5 and also linuxnewbieguide.org/content/paritioning-disk to see how to partition your disk.
Every Linux distro I've come across can dual-boot with Windows.
It is a good idea to install the Windows OS first. You may already have done this, in which case you will have have to partition your hard drive to accomodate the Linux operating system. Ali Ross' link will show you how to do this.
From personal experience, I would advise adding a second hard drive into your computer and installing Linux onto that.
Hi Diana,
In short, the answer is yes. The GRUB bootloader will boot any operating system you like. Debian isn't as newbie friendly as other similar Debian based distros such as Ubuntu at doing this, but please have a look at Chapter 5 and also linuxnewbieguide.org/content/paritioning-disk to see how to partition your disk.
Hope this helps.