I know, I know... not really an answer to your question directly, but still totally worth mentioning IMHO. Why ask the user to type out a path (and chance typos) when you can just pop up a Open File dialog box? Drop this function at the beginning of the script:
function Get-FileName($initialDirectory)
{
[System.Reflection.Assembly]::LoadWithPartialName("System.windows.forms") |
Out-Null
$OpenFileDialog = New-Object System.Windows.Forms.OpenFileDialog
$OpenFileDialog.initialDirectory = $initialDirectory
$OpenFileDialog.filter = "All files (*.*)| *.*"
$OpenFileDialog.ShowDialog() | Out-Null
$OpenFileDialog.filename
}
Then when you need to get a file name and path you can just do $file = get-filename
and be done with it. If you only want certain file types you can change the filter line to only allow the user to see certain kinds of files, or even a specific file name (i.e. you need them to locate 'computerlist.csv' on the hard drive or something, you can change the . in the filter to computerlist.csv).