Left (non-drive side, adjustable) are all generally right-hand (standard) threaded. Your friend was likely talking about the right (drive-side, fixed) cup, which for modern bottom brackets is left-hand thread for British/ISO and right-hand thread for Italian.

I don't know a lot about French bikes, but your Peugeot likely uses the now obsolete French threading, which is different than the British/ISO and Italian standards of today.

Bottom bracket sizing: http://sheldonbrown.com/gloss_bo-z.html#bottom
French bottom brackets: http://www.sheldonbrown.com/velos.html#bottom

You may be better off inspecting the cups and spindle races and if they are okay, then just replace the bearings.

Edit: Oh and it is supposed to be the nicest weekend we've had in months here, but I'll be stuck inside with the flu.