High-definition DVD has arrived … in two, incompatible formats — Blu-ray Disc and HD DVD.

Both formats offer capacities several times that of conventional DVDs. At launch, Blu-ray Disc is available in 25GB single-layer and 50GB dual-layer flavors (for prepackaged media as well as for recordable and rewritable media). By contrast, HD DVD’s capacity comes in at 15GB for a single-layer disc and 30GB for a dual-layer disc (for prepackaged and recordable media; rewritable media will be 20GB for single-layer discs).