vSphere Client doesn’t show Hardware Status tab when you login to vCenter Server, it is due to vCenter Hardware Status Plugin is not running on vSphere Client. Try enabling this plugin to see if it helps.
If you get an error message like below, and you are running Windows 2003 (maybe XP, too) then your system where vSphere Client is installed is missing a update.
Obtain and install this hotfix from http://support.microsoft.com/kb/948963. Then restart the system.
After restart, you got your Hardware Status tab back, and plugins are running fine.