The downloadable Data Lifeguard Tools now comes in both DOS and Windows versions and was written specifically for the installation of Western Digital EIDE hard drives. If your computer system already has a hard drive installed with an operating system of Windows 98SE or greater, you should use the Windows version of Data Lifeguard for best results. The DOS version is required if installing a hard drive in a new system without existing operating system support. If you plan on copying the contents of a boot drive, Western Digital recommends using the DOS version of Data Lifeguard Tools.