I am posting from my new Mac.

[Xantar]

To add to Gekko's list:

VLC. Plays every movie format under the sun and does it seemlessly. It even handles those encodes which have subtitles you can turn on and off or different audio tracks you can switch between like a DVD.

Oh, and you should take a look at the Widgets, too. Gekko will know a good website for those (I just Google for them).

[GameMaster]

I'm hoping to get a new Mac soon. Right the now the contenders are a refurbished G5 iMac or the new Intel CoreDuo Mac Mini.