(Not an answer; correction of comment)
Originally Posted by eSelix
Do you known that installing other operating system it will delete your Windows? You need to have free partition. Do you have it, or do you really want to remove Windows?
You can install Ubuntu along with an existing Windows with the normal installer on the Ubuntu CD. Select "Install Ubuntu alongside Windows" and the installer will automatically re-partition the disk. As usual before re-partitioning disks, make a backup of valuable data on your Windows partition first.
and for nice screenshots see https://help.ubuntu.com/community/GraphicalInstall
(except in step 5 "Allocate drive space" select "Install Ubuntu alongside Windows").