Some of you might be adventurous and be going to update you machine to the Windows 7 RC. I you have the chance it is an amazing update. Just recently Microsoft announced the availability of Windows XP Mode and Windows Virtual PC.
Windows XP mode is a pre-configured Windows XP VM that you can use on Windows7 while you may have a use for this for an old application you would have to install AX into this environment. You can continue to use the AX2009 VMs with Windows Virtual PC.
See the Microsoft site http://www.microsoft.com/windows/virtual-pc/default.aspx on the details.
If you want to give it a try then it is pretty easy to keep your AX2009 VMs running.
See my note posted earlier on the future also with Hyper-V for the AX2009 VMs.