GroundZero3

Download and install vpshere CLI for windows

Download the latest update for esxi
Download

Shut down all virtual machines and put the esxi box into maintenance mode.

Once you got the download you want to install go to START > Programs > Vmware > VMware vSphere CLI > command prompt

I made it easy on myself and copy the esxi update in .zip format to C:\Program Files\VMware\VMware vSphere CLI\bin (I also extracted the zip file)
You start off in C:\Program Files\VMware\VMware vSphere CLI in the DOS prompt.

If you do a dir you will see a folder called bin (go into that directory)

Next you will run the command:
C:\Program Files\VMware\VMware vSphere CLI\bin>vihostupdate.pl --server x.x.x.x --username root --password xxxxxxxxx -b ESXi410-201107001.zip –l (the name will all depend on the update you are installing) This was the latest update on 9/16/11

You should get a response back that is similar
---------Bulletin ID--------- ----------------Summary-----------------
ESXi410-201107401-BG Updates Firmware
ESXi410-201107402-BG Updates VMware Tools

Next you will want to run the command:
vihostupdate.pl --server x.x.x.x --username root --password xxxxxxxxx -b ESXi410-201107001.zip –i –B ESXi410-201107401-BG

You will get this response:
Please wait patch installation is in progress ...

Once it’s completed it should show this:

The update completed successfully, but the system needs to be rebooted for the changes to be effective.

I also ran the install for the vmware tools update!!
C:\Program Files\VMware\VMware vSphere CLI\bin>vihostupdate.pl --server x.x.x.x --username root --password xxxxxxxxxxx -b ESXi410-201107001.zip -i -B ESXi410-201107402-BG

You will get this:
Please wait patch installation is in progress ...

And this when it’s completed:
Host updated successfully.

Reboot host, exit maintenance mode and start up your virtual servers!

Since you updated the vmware tools you will need to install that on every single virtual machine!