well, in that case!

if ($^O =~ /win32/i) {
   # do stuff with xcopy
} else {
   # do stuff with cp -r
}
[download]

I am *not* advocating this solution... I just thought it would be cheesy way to do it. Please, for the love of anything you may or may not hold holy, use something like File::Find or File::NCopy instead like merlyn suggested.