That's not how it works...answers here.
When you installed Linux, what options did you select for setting up a boot loader? What do you get at start-up?
If there is no boot loader, you cannot get in to anything. You can use a live CD distro like Knoppix to install grub (boot loader).
You can get Windows back by booting with the windows install CD--rescue mode. when you get to a prompt, type "fixmbr"