Enchantress, Australia is actually PAL region 4.
If your PAL dvd player is region free it will work, if it's not, i'm not sure but i think many Australian releases are double duty coded Region 2/4, i'm sure someone here will confirm it.
EDIt: ohh so 2099net got the info in while i was typing. darn! foiled again!
As for the double disc PAL "Dark Red Velvetium Editium" (my term

) i think it's great specially if you love the movie. I haven't seen the single disc PAL one so i don't know exactly how are they different. But this is one case i would buy it for the ancient book case look alone
Just in case, Platinums tend to have other names in different countries ;P
Saito, maybe when you said the "rarest" you were refering to as "hard to find". Indeed discontinued Platinums tend to become scarce and harder to find tho they sometimes pop up out of nowhere for limited times
Other "rare" discs are the Treasure series. Check the Out of Print page on this web site for titles that are going bye bye or have already (hint: Certain Lion is going bye bye soon), if those are the "rarities" you were seeking
Oh and a double welcome then to the both of ye!