As most of you know already, Windows Vista is knocking at the door and should normally be on the market early next year. There are many things you can do to get ready to this upgrade.
If you're part of the Customer Preview Program then you do have access to the installation files. If you're not part of it, the MSDN kit will make Vista available. If you're neither in the Customer Preview Program nor an MSDN Subscriber, you'll have to wait until RC1 to get the bits.
It's also recommended you test if your machine will be able to run Vista at its best. There is a small test application called the Windows Vista Upgrade Adivsor Beta that you can download and run. This will tell you how safe (or unsafe) it is to run Vista on your existing machine.
For the software upgrade itself, there are some restictions on the type of software upgrade you can do. Some transitions will require a clean install, and some others will support in-place upgrade. There's a table that helps you identifying all the possible combinations. Of course, if you need to do a clean install, there's a tool you can use to transfer your settings from your old to your new machine. This tool is the User State Migration Tool or the Files and Setting Transfer Wizard. This tool starts up automatically as you install Vista.
For more information, go and visit the Windows Vista site or the Vista Developer site.