First I wanted to know which version of IIS is installed on the server. So, I got the following from here.
You can look at %SYSTEMROOT%\system32\inetsrv\inetinfo.exe. Right-click and get properties, click the Version tab.
The IIS version in my case is 6.0.3790.3959.
Now I also want to know If there are any patches installed for IIS. If yes, how to view them as a list?