Installing ESXi on a Dell PowerEdge server with IDE drives
However, one of the non-redundant configurations ESXi does not support is IDE drives in a non-RAID configuration. Fortunately you can configure ESXi to install on IDE drives, but you effectively trick it into believe the drive is a SCSI drive.
The installation instructions can be found on the following website, but be aware that this is an unsupported configuration and support from VMWare may be very limited.
http://www.vm-help.com/esx/esx3i/ESXi_install_to_IDE_drive/ESXi_install_to_IDE_drive.php
Enjoy!