had similar symptoms with the my03 recently
in my case if i was steering even slightly to the left i would hear the squeal
it wouldnt necessarily occur under braking conditions

i ditched the stock stuff for dba4000 slotted rotors and ferodo ds2000 pads 3 weeks ago (44000kms). very nice combo.. brake performance is pretty impressive at the moment and could get better over the coming weeks as the pads settle in further