To download the vSphere Client for ESXi 5.3 or 5.5, you'll need to visit VMware's official site or search for the exact version in their archives, as those older clients aren't readily available anymore.
This is the stock ESXi 5.5.0 VMvisor installation ISO from VMware, however the net-e1000e driver has been swapped with the one from ESXi 5.0 for compatibility with older gigabit controllers.
Download the file to a folder on your hard drive, then create a CD using your preferred CD burning software. To ensure the integrity of your download, please verify the checksum value. By downloading, you accept the terms of the Dell Software License Agre
Yesterday VMware has finally released the final release of VMware vSphere 5.5 which is GA and available for download. The whole vCloud suite and vSphere products including ESXi 5.5 are available at VMware.