Never ran the upgrade advisor, yet I'm running Windows 7 RC1 on one of my older boxes for testing purposes. This machine was built a while back, right before WoW beta came out, so in today's standards it's not a great machine. It does however run most modern games on low graphics settings without problems. This machine previously had XP on it.
That being said, so far I have had no problems with Windows 7. In fact, I'm still a little suprised how well it works compaired to Vista (which I run on one of my machines and have a number of reasons why I dislike).
I have had no problems running Impulse or Demigod on my Winows 7 machine.
Let me know if you have any further questions re win7 from my experiences.