Note that Win32API::File has a nice advantage over the other modules previously suggested in that it is part of libwin32 and so comes preinstalled with Win32 binary distributions of Perl.

    use strict;
    use Win32API::File qw(
        getLogicalDrives GetDriveType :DRIVE_ );
    for my $root (  getLogicalDrives()  ) {
        my $type= GetDriveType($root);
        if(  DRIVE_FIXED == $type
         ||  DRIVE_RAMDISK == $type  ) {
            ....
        }
    }
[download]

Since you probably don't want to search the floppy, CD-ROM, unpartitioned, nor network drives.

        - tye (but my friends call me "Tye")