mjn, Macrovision own Cactus Data Shield, a cd protection method, which afaik is pretty old at this stage.
To answer you question SHANTY, It's not normally labeled on CDs, however just look for a "you may experience problems with PC" label or "won't play on CD-ROM drives"... I don't think theres any law that states they explicitly have to have such labeling.
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Arcam CD72t->Van Den Hul Bay C5->Musical Fidelity X-Can V2->Sennheiser HD580