Today I installed the beta version of Windows 7 on my laptop on top of my Vista. My Vista already had an AX installation, but it didn't work after the upgrade to Windows 7. So I re-installed the developer flavour of Dynamics AX 2009 (all on one box), and pointed it at my exisitng DB. And without having to install any drivers or other updates I had AX2009 RTM running on Windows 7.
If you get the chance; make sure to take Windows 7 for a spin.