On-demand HDTV now on XBLM

The premise of letting people watch what they want to watch whenever they have the impulse to watch it is a powerful profit-driver. Just ask TiVo, or any cable or satellite TV provider offering on-demand pay-per-view.

Microsoft's bid to tap into that on-demand desire launched today. The company is offering dozens of downloadable films and TV series through its Xbox 360 Marketplace. The company announced the initiative earlier this month, along with six content partners that would help to populate the service with initial offerings.

For the service's launch, Microsoft is offering 48 movies for rent, with a handful of them available in high-definition (720p) downloads as well as standard-definition (480p). Downloaded movies remain on the hard drive for up to two weeks, but once a user begins watching the movie, it is deleted 24 hours later. For that period, however, the movie can be viewed as many times as the purchaser wants.

The initial lineup is a wide-ranging sampling of films from cherished classics (Rebel Without a Cause, Chinatown) and art-house fare (Akira Kurosawa's Dreams), to recent hits (V for Vendetta) and curios and oddities (Ballistic: Ecks vs. Sever, Pootie Tang, Congo). Films available in high-definition include ATL, Clash of the Titans, V for Vendetta, Unforgiven, Poseidon, and The Perfect Storm.

There are two pricing structures set up for the film rentals. New movie rentals cost 320 Microsoft points ($4) for a standard-definition download, while the high-definition option will run 480 Microsoft points ($6). For older movies, the 480p download will set users back 240 points ($3), while classics in 720p are offered for 360 Microsoft points ($4.50).

Space could quickly become a concern for gaming film buffs, because some of the service's longer films (around 130 minutes) can eat up 1.7GB in standard definition and top out at 5.7GB in high definition. The only hard drive currently available for the Xbox 360 is 20GB, and it typically holds a user's Xbox Live Arcade games, gamer pics, themes, game demos, ripped music, and game saves.

On the TV side of things, gamers can purchase episodes or download free clips from 47 series. In addition to a wealth of animated humor programs like Aqua Teen Hunger Force, South Park, and Beavis and Butthead, the service offers more straight-faced fare, including dozens of episodes of CSI and its offshoots, a season's worth of the original Star Trek, and selected Ultimate Fighting Championship matches.

Pricing is a little more uniform for the TV shows. Standard-definition downloads will cost users 160 points ($2), whether it's an 11-minute episode of Frisky Dingo or a 44-minute installment of NCIS. High-definition episodes are available only for select shows (CSI, NCIS, and Jericho, to name a few), and each one will set users back 240 points ($3).

The Marketplace also hosts free clips for a handful of shows, including Late Night with Conan O'Brien, The Family Guy, and Viva Pinata, created in conjunction with the Xbox 360 game of the same name. A 44-minute TV show in high definition can take up as much as 2GB on the Xbox 360 hard drive.

Each studio will set its own release dates. Microsoft expects TV shows to be available on Xbox Live the day after they air on television, just as they're made available online by some networks. Some of the shows are already up to date. For instance, the service is offering the "Stanley's Cup" episode of South Park, which premiered last Wednesday.