Once only available through the Apple TV, HD movies can now be purchased or rented directly through iTunes on Macs and PCs.

The company now says that customers of the US iTunes Store can buy new-release movies in 720p directly from iTunes for $19.99 and rent them for $4.99 within 30 days of their being made available for sale. Many older titles are also available for rent in the HD format for $3.99.

As with TV shows, each HD copy also comes with a standard-definition version of the movie that can be transferred to an iPhone or iPod, neither of which yet supports HD. The initial lineup of HD rentals includes pre-orders for the Bond movie Quantum of Solace as well as Twilight and is focusing on new releases.

An HD Movies page is currently highlighting those titles that are already available at the increased resolution. Using the feature requires iTunes 8.1 or higher and a Mac or Windows PC capable of smoothly playing HD movies.