If you wish to migrate to Plesk 7.5 from another hosting platform or earlier versions of Plesk, and cannot afford additional hardware for this operation, you can do it in one of the following ways:
Plesk cannot be installed on the machine running other control panel software. To circumvent this limitation, you need to create a kind of virtual environment, such as chroot. Plesk can be installed into chrooted environment in a special mode. Once Plesk is installed into the chrooted environment, you can migrate data from your hosting platform into the chrooted environment. After successful completion, you will be able to shut your previously used hosting platform down and use Plesk as your main control panel.
You should have a hard disk with operating system and Plesk software installed. This feature allows importing to Plesk the data gathered by migration agent. Once the data are obtained, you will have to move them to the disk with Plesk installation and reboot to the operating system where Plesk is installed. After successful completion, you will be able to remove your previously used hosting platform.