Oh, definitely follow up on paco's ground-breaking node -- you haven't been at perlmonks till you've been there. I'm serious.

But I'll add one more option (shameless plug): An alternative to File::Find -- I know, I know... lots of monks think it's dirty somehow to use an existing utility program in a subprocess to do something that a perl module can do. But "find" is available on all unix systems (including MacOSX, of course), it's easy to get an MS-windows port (find.exe) from numerous great sources, and (ahem) it's just faster and easier in all respects when compared to File::Find. Just my $0.02...