I've become comfortable with XP / MSE now I have found my way around the behind the scenes stuff. I thought there could have been more available on the MSE interface in the way of logs, reports, etc...but thats just me. I am pleasantly surprised by the new development in Microsoft. Still only running it on one computer.
I'm unfamiliar with Windows 7 but have been fielding a few enquiries lately. No one running the 7 beta round here, so I guess I'm going to have to be the early adopter if I find the time.
I quite like the idea of having the option of a resident antimalware, if that is what MSE is going to be. And then I have mbam on the bench for when I want to use it, plus a few other tools. I cannot help but feel Windows 7 with MSE will become something of a standard from 2010. I would be running avast as resident antivirus with that combo, of course. Though still a bit of time to play out.