WINSXS folder: what can be discarded?

On running a system file inventory to verify that everything was patched on
a new Vista test box which had all the current maintenance from Windows
Update installed, the scanner flagged several instances of IEXPLORE.EXE,
some downlevel, in the C:\WINDOWS\WINSXS folder tree.

This folder is (vaguely) documented by Microsoft as the "side-by-side"
resource used to handle applications which need specific versions of a DLL;
this appears to be how it's used in Windows XP.

I've seen passing references to it also being used to hold uninstall
information for some patches.

In Vista, however, even at this very early stage in the life of the system
it's got significantly more content, and as noted earlier includes obsolete
copies of IE.

So...two questions:

1) Where can I find decent documentation for the WINSXS folder?

2) Is there a programmatic way to identify and remove from WINSXS files and
folders which contain material obsoleted by security udpates without
suffering side effects? Or can I justify ignoring any downlevel files in
the folder tree?

Joe Morris