There are a few different ways to determine which version of VMWare you’re running.
VMware Infrastructure Client:
From the VIC there are a few ways of finding the ESX build number.
The first is by clicking on the ESX server in the VIC and selecting the Summary tab. The ESX version and build number can be seen along the top of the row of tabs.
A second way is to select Help –> About VMware Infrastructure. An About box will be displayed which gives both the VICs version and build numbers along with that for the ESX server itself.
A third way is by generating an HTML based summary report on the ESX server. To generate a report right mouse click on the ESX server you want to run the report against and select Report Summary.
From your ESX server or service console, issue the command below:
This will return the version information like the example below.
VMware ESXi 4.1.0 build-260247