Win32 has native abilities to do this.

On all Win32 OS's, you can use FindFirstChangeNotification et.al. You can access Windows API functions with Win32::API, or many are already wrapped in nice Perl modules. I used this once from Perl just in playing around, so I know it can be done.

On NT/2000/XP, you can use ReadDirectoryChangesW which gives more detailed info than "something changed!". On 2000/XP (I think it started in win2k) there is a similar feature that's sticky, and can report changes that occured even when you were not running and activly watching for them.

—John