Why can't they show the total size of a folder in the new Details Pane or
even in the status bar like in XP, when nothing is selected.
Don't think XP did this either, the problem is when the folder contains
other folders, then all folders will have to be recursively traversed to
get the size of all files in those folders. The problem with this is
that when you have lots of subfolders with lots of files in it this
operation will take quite a lot of time.