It's not a hash that you want... it's probably an array of arrays. What if there were duplicate keys? your hash will eat them up and you'll end up with only the last entry.

print "With Hash:\n\n";

$save = tell DATA;

while(<DATA>) {
     my ($k, $v) = split '\|';
     $hash{$k} = $v;
}
print "$_|$hash{$_}" for sort { $a <=> $b } keys %hash;

seek DATA, $save, 0;

print "\n\nWith array:\n\n";
while(<DATA>) {
     my ($k, $v) = split '\|';
     push @arr, [$k, $v];
}
print "$_->[0]|$_->[1]" for sort { $a->[0] <=> $b->[0] } @arr;

__DATA__
30|microsoft
70|aol
76|netscape
5|trouble?
35|mozilla
30|die microsoft
40|opera
100|FireFox
5|no more trouble
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