In XP, if I opened up Windows Explorer, it remembered its previous size and position settings between closing and opening it.
In Vista, it often doesn't, and goes back to a default size that is too small for my liking, so I have to resize it. I don't maximise it since then it's too big. If I open Windows Explorer, resize it, close it, then immediately open it again, it does remember it's size. But when I close it and do some other things then open it again, it often (though not always) goes back to the default small size.
Yes, I have seen this too with IE7 and both XP and Vista. I have found that if I close Explorer by clicking and closing on the IE icon at top right, instead of the X at top left, I have stopped this problem. I suspect it my be more an issue of IE7 than Vista.