1 - Create a Virtual Machine with custom settings.
2 - Select the new Virtual Machine version 7 hardware.
3 - Select Red Hat Enterprise Linux v5 (64-bit).
4 - 1 vCPU and 1GB of RAM will suffice.
5 - I used the LSI Logic Parallel SCSI Controller.
6 - Create a disk based between 20 – 30GB (less has caused issues, see comments below)
7 - Make it thin provisioned if you want, why wouldn’t you?
8 - Connect the ISO image to the VM and start it.
9 - Follow the prompts on screen to complete the install.
ref: http://www.virtualpro.co.uk/2009/06/22/how-to-run-citrix-xenserver-55-on-vmware-vsphere/
