actually, you should use:

use File::Spec 'catfile';

## later, in sub wanted...
if( -d catfile( $File::Find::dir, $_) 
    && m/\A_/)
{
    $File::Find::prune= 1;
    return;
}
[download]

you need to specify the absolute path to the file system object you're accessing. $_ stores the name relative to the current search directory within File::Find. also, File::Spec will give you the platform independence you secretly crave ;P

but, overall, i'd still suggest broquaint's method. File::Find::Rule makes code like this easier to code, understand, and maintain.

~Particle *accelerates*