If Mageia didn't convince you or you can't install it correctly, in short you want get rid of it. That is your right and Mageia give you also the possibility to be uninstalled. That is not true for every operating system. After your data backup, reboot on your Mageia DVD and select Rescue system, then, Restore Windows boot loader. At the next boot, you will only have Windows without any menu to choose your operating system. To get back the space used by Mageia partitions on Windows, click on Start -> Control Panel -> Administrative Tools -> Computer Management -> Storage -> Disk Management to access to the partition management. You will recognize the Mageia partition because they are labeled Unknown, and also by there size and place in the disk. Right click on one of these partitions and select Delete. The space will be freed. If you have XP, you can create a new partition and format it (FAT32 or NTFS). It will get a partition letter. If you have Vista or 7, you have one more possibility, you can extend the existing partition that is at the left hand of the free space. There are other partitioning tools that can be used, such as gparted, available for both windows and linux. As always, when changing partitions, be very careful, and make sure all important things have been backed up.