You can ignore this message for now, as you can move this virtual machine to a drive that can fit it. The virtual disk's size should be large enough to hold the guest operating system and all of the software that you intend to install in the virtual machine, with room for data and growth. You cannot change the virtual disk's maximum capacity later, although you can install additional virtual disks if you run out of space on this one. For example, you need about 500MB of actual free space on the file system containing the virtual disk to install Windows NT 4.0 and popular applications such as Microsoft Office inside the virtual machine. Enable the CD-ROM drive.
Most operating systems require the use of a CD-ROM for installation.
Leave this option set to auto detect. If you have more than one CD-ROM installed on your machine, you may select which drive letter to use. Otherwise, you may leave the option set to auto detect. Enable the floppy disk drive. Select the floppy drive, typically the A drive.