for(my $x=0; $x<$#files+4; $x+=4) {
    @four_files = @files[$x..$x+3];
    print Tr( {-align=>'center'}, td( submit(-name=>'file', -value=>$four_files[0] )),
                                  td( submit(-name=>'file', -value=>$four_files[1] )),
                                  td( submit(-name=>'file', -value=>$four_files[2] )),
                                  td( submit(-name=>'file', -value=>$four_files[3] )));
}