force PowerShell to wait for cmdlet execution to end

Before I forget, credit where credit is due for as far as I've gotten: the following code is adapted from http://mow001.blogspot.com/2006/01/msh-out-zip-function.html.

Okay, here's my challenge: I would like to create a function that will accept a series of filenames (full paths) as arguments, and zip them ONE AT A TIME to the same folder and filename, but with ".zip" appended.

So [PS> zipfiles "g:\test\file1.txt" "g:\test\file2.txt"] will generate [g:\test\file1.txt.zip] and [g:\test\file2.txt.zip].

Here's something that works:

function zipFiles {
  for( $i = 0; $i -lt $args.length; $i++ ){
    # Define the source and destination file paths.
    $FileName = $args[$i]
    $ZipName = $FileName + ".zip"
   
    # Create code to zip the file.
    $cmds = ' $' + "ZipFile = (new-object -com shell.application).NameSpace('$ZipName');"
    $cmds += ' $' + "ZipFile.CopyHere('$FileName');"

    # Execute the code in a separate process and wait for it to exit, so we won't overload the machine.
    write-host "Zipping '$FileName...'"
    set-content $ZipName("PK" + [char]5 + [char]6 + ("$([char]0)" * 18))
    [diagnostics.process]::start("powershell", "-noexit -command & {$cmds}").waitforexit()
    write-host "...done."
  }
}

...BUT the "-noexit" is highly undesirable, since there are a lot of files to be zipped and I would like to be able to start it and walk away, rather than sit there and close the secondary window for each file.

The problem is, if I remove the "-noexit" it doesn't work.  The secondary window doesn't wait for CopyHere() to finish; it just opens and closes in a flash without doing anything.

The ideal solution would be something that tells PowerShell to wait for a given cmdlet to finish executing before going on to the next such that the secondary window wouldn't even be necessary.

Hopefully the solution is obvious to the Shellistas here, but I'm new and confused.