Under Windows, the WMI supplies this information. I wrote a module, DBD::WMI, which makes access to the WMI via WQL possible:

#!/usr/bin/perl -w
package main;
use strict;
use DBI;

my $dbh = DBI->connect('dbi:WMI:');

my $sth = $dbh->prepare(<<WQL);
    SELECT * FROM Win32_TemperatureInfo
WQL

$sth->execute();
while (defined (my $row = $sth->fetchrow_arrayref())) {
    my $temp = $row->[0];
    print join "\t", $temp->Name, $temp->NominalReading, $temp->Curren
+tReading;
    print "\n";
}
[download]

According to the MSDN, this query should give you all readings from all sensors, but on my (Win2k) machine, no temperature probe is returned, so I don't know whether this is a problem with my program, with Win2k, or whether my mainboard doesn't have any supported temperature sensors.

According to Google Groups, not all mainboard drivers support the WMI, so you might be out of luck there.

The WMI provides lots of management information about Windows and Windows machines - it's well worth a look.