You can grab it from:

It has a bunch of bug fixes - most notable mentions include:

  • Improved performance for XP SP2 as a guest
  • Bug fixes for running on Athlon and Prescott processors
  • You can now use DOS Folder Sharing and EMM386 at the same time (yay!)

Plus a whole bunch of other goodness.

There have been a small number of reports of problems installing the upgrade though (bummer) - but they all seem to be resolved by uninstalling and reinstalling.