I took it a step further and "pimped my script"
#define variables
$process = "c:\Program Files (x86)\7-Zip\7z.exe"
$destinationFile = "c:\temp\testfile.zip"
$sourceFile = "c:\temp\*.xls"
$password = "password123"
#define functions
function balloonPopup($message){
[system.Reflection.Assembly]::LoadWithPartialName('System.Windows.Forms') | Out-Null
$balloon = New-Object System.Windows.Forms.NotifyIcon
$path = Get-Process -id $pid | Select-Object -ExpandProperty Path
$icon = [System.Drawing.Icon]::ExtractAssociatedIcon($path)
$balloon.Icon = $icon
$balloon.BalloonTipIcon = 'Info'
$balloon.BalloonTipText = $message
$balloon.BalloonTipTitle = 'Done'
$balloon.Visible = $true
$balloon.ShowBalloonTip(10000)
}
#script body
$p = Start-Process $process -ArgumentList "a $destinationFile $sourceFile -p$password" -Wait -PassThru
...