http://www.appleinsider.com/article.php?id=2612

Atop the list of enhancements delivered in the new version is 32-bit support for Windows Vista......
and updated the software drivers for trackpad, AppleTime (synch), audio, graphics, modem, and iSight.
Don't look like ti will support Vista 64bit..... a shame really, I would like to do some benchmarking of 10.5 Vs Vista on the same hardware but oh well.....