Glad you mentioned that, I forgot to make note of it...Vista, like you said, will easily consume 45-50% of my 2GB of RAM on boot...I have a tweaked services set and a few programs running on boot...
W7 uses about half that much...I am seeing 24-36%...I've been on for a few hours now, running the RAM hungry FF3, and this is my TM screenshot:
Clearly, you can see they've really tried to improve the memory management issues...And with so many small improvements, I don't have to install so many little 'handler' programs...