You want to do a dual boot?

First your going to have to repartiton the drive.

What filesystem is your windows?

If its NTFS try your best to get all the files near the begining (defrag.)
That way you can use Qt parted wthout to much trouble, or even better use some commerical software that can move the windows files around as it makes the linux partition (still with me?)

Then refer here http://www.knoppix.net/docs/index.php/HdInstallHowTo

on how to install.

On the case of chooseing which one you want to boot you could use Lilo, though I don't know how to install it.