If you have a machine that was first installed from the 2007 cd and it has been continuously upgraded, there is nothing to do. If you have an install directly from the 2007 disc, but without upgrades, you need to download the 2009.2, or Minimi 2009.4, or one of the other desktop versions and then upgrade from there. There are still a ton of upgrades, but it should work relatively well and if you have problems, others will be able to help you get going. Also, there will be a newer release someday, but there is no reason to wait.
Galen