a Motown-like tune playing during the party scene at beginning of movie Mission Impossible III that I want to download but remember what it is?

You're likely thinking of the song "Get It On" by T. Rex. While it's not exactly a Motown song, it's got that classic, upbeat energy that's perfect for a party scene, especially one with a bit of a retro vibe.

The song is featured prominently in the opening party scene of *Mission: Impossible III*, creating a fun and energetic atmosphere for the film's introduction.

If you're looking to download the song, it's widely available on major music streaming platforms and digital retailers like iTunes.