Memory did you bother to read anything that is posted in the Win7 sticky? I gave out almost all of this information there already. Along with answered just about every question you have asked here, multiple times. I know for a FACT that i have answered that removal of Win7 question and what can happen. I had a big back and forth on it with several people in the Win7 thread. Please READ that topic to get answers. They are there.
Darsunt,
Vista is known to be a resource eater. But it can be tamed.
Hibernation turned off by the run prompt
Shadow Copies turned off
Ssytem Restore points limited to 5
Pagefile on a separate partition and many more tricks will cut the cost of using Vista down greatly.
Win7 is not as intensive as Vista. I have 18GB of space used up. For Win7 and all of my main programs. this includes 5 browsers and Office 2007 Ultimate. My XP install has 32GB of space used. Which does include my Steam games as well. But even if you take those off i highly doubt you will make up the almost 16GB of space difference in space used from XP to Win7 when i have the same set of programs installed on each. Including Office.
So Win7 is by far less intensive. It is even starting to get more slim than XP.