The steps to install the offline bundle for VMware ESXi 5.0 has changed from VMware ESXi 4.X. The vihostupdate command used in ESXi 4.X does not work against ESXi 5.0 hosts.
1. Download the bundle.zip.
Either Google “HP ESXi Offline Bundle for VMware ESXi 5.0” or go to www.hp.com → Support & Drivers → Drivers & Software → Search for the server model (e.g. ProLiant BL640c) → Select the server series → Select operating system = VMware ESXi 5.0 → Find “* RECOMMENDED* HP ESXi Offline Bundle for VMware ESXi 5.0 → Download