I want to run something like the below script every 10 minutes.

I have file A and file B. Every 10 minutes, I want to check if File A is newer than File B. If so, I want to set the LastWriteTime of file B to the current date. I believe my `if` statement is wrong... How can I fix it?

```
$a = Get-Item c:\users\testuser\desktop\test.xml | select LastWriteTime

$b = Get-Item C:\users\testuser\Desktop\test.swf | select LastWriteTime

if($a < $b)
{
    $b.LastWriteTime = (Get-Date)
}

```

I think in the above example, I'm only setting the variable $b to the current date...I want to set the LastWriteTime of the actual file to the current date.