I have a series three also (dec '05), If you open up the glove box where the Nav DVD thing is you should see a bluetooth logo.
From what I remember if it has bluetooth it is a premium series 3. Mine has the 19's, half leather and steering controls, bi-xenon, dual climate but no bose. Unless it actually says Bose on the MD player then its not. Not sure about LSD etc. After the first couple of years almost everything seemed to be factory options etc so it just got hard to tell. But i'm fairly certain that if it has Bluetooth, its a premium.