My test system was running an Intel Core 2 Duo T7250, which is clocked at 2.0GHz with an 800MHz Front Side Bus and 2MB L2 Cache. It had 2GB of 667MHz DDR2 RAM and 5400rpm 250GB SATA HDD, with graphics supplied by an nVidia 8600M GT.
First, let's take a look at results from PCMark Vantage:
Looking at the Overall score it is clear there's some improvement, with over a 200 point increase. However, it's more interesting to see where the improvements come. There's some notable improvement in the TV & Movies segments, which consists of both video playback and encoding tests. A similar level of improvement can also be seen and Music Suite, which mixes encoding with other tasks such as web page rendering of an online music store.
Most interesting though is the Communications Suite, which sees a more significant increase of just over 500 points. Of all the tests this could be argued to be one of the more demanding, with two of the four tests consisting of three simultaneous tasks - including web page rendering, data encryption and data compression all at the same time. With the TV & Movies and Music Suites also featuring CPU intensive tasks running simultaneously, there's some credence to the idea that Vista is dealing with multiple threads more efficiently.