Installing Reactos using your internal drive.
1. Back up your drive. This method will wipe your drive.
2. Boot from a linux live cd. This will allow you to perform the necessary actions with your drive.
3. Download and unzip the Reactos bootcd.
4. Write the .iso to the entire head drive, not to a single partition. Using Gnome Disk Utility, select the drive from the left. Then "Restore Image" from the dropdown menu at the top. This shouldn't take more then a minute.
5. After writing the image, reboot to the drive. Follow the installer like normal, but create and use a second partition to install to.
6. When ready to update, you should be able to write the disk image to the first partition instead of rewriting the entire disk. Then just have freeldr boot from the first partition.