I knocked this up just to make it easier to get the model, BIOS versions and serial numbers/ service tags (only tested against Dell machines so far). I haven’t commented it because hopefully the variable names are evident enough.
$computerDetails=Get-WmiObject -Class Win32_ComputerSystem
$BIOSDetails=Get-WmiObject -Class Win32_BIOS
Write-Host “The model is” $computerDetails.Manufacturer,$computerDetails.Model
Write-Host “With BIOS version” $BIOSDetails.SMBIOSBIOSVersion “and Serial number” $BIOSDetails.SerialNumber