Not a bad response. Your point about not seeing the process manager I'd thought about myself.
However, there's historical context to be considered.
Microsoft has a track record of bloatware. The final product may "only" need 600. 500.
Any way you cut the cake I'm sure we could all say it's a safe assumption to make that Vista will eat alot more than XP currently does. Most average xp installs that I've seen eat up about as much memory as OS10 does, about 250-350MB.(and in both instances those are too much as well, nevermind what's coming out in the near future)
I'll believe it when I see it, but until there's something more solid than anonymous reports from shadowy people reported by trashy rumor mills, I'm going to be a bit skeptical ;)