I recently used VMWare Standalone Converter to migrate a physical Windows Server 2003 machine to a Virtual machine Infrastructure host. However, the machine would not boot up on ESXi 4. All that appeared on the screen was a white, non-blinking cursor at the top left of the screen.
Turns out, after a lot of troubleshooting, that ESXi can't handle virtual IDE drives - they must be SCSI, either LSI Logic or Bus Logic. After following this guide to setup SSH on ESX server, I then followed the instructions at the VMWare help site to convert the virtual IDE disk to SCSI (with LSI Logic controller). I used vi to edit the required file, as nano is not available on ESXi.
After the conversion was complete, the machine booted perfectly.