Use powershell to update / install exe

hello ate,

i want to write a ps script that will auto download exe file from suppliers site
(e.g. http://www.suppliers.com/file.exe)

then after the download the scripts will check if existing file on local computer has already same file version with new download – if it is, scripts will not continue to run the exe and end the command

else – the file.exe will continue install and update the current installed application on local computer – then output reports to c:\file.log

what i have done so far is below and im not positive after this

ps
(New-Object System.Net.WebClient).DownloadFile("http://www.suppliers.com/file.exe","C:\support\file.exe")
& 'C:\support.exe' /q

(Get-Command "C:\Program Files (x86)\Uni\Bin\Uni.exe").FileVersionInfo.Fileversion

thanks heaps!