In Windows Vista, how can I find all the files for which a user has access permissions?
You can use the Vista icacls command with the /findsid parameter to find all files that contain a specific SID in the file's ACL. The following example shows the command syntax:

ICACLS *.* /findsid savilltech\administrator /t /c

where /t means to perform the operation on the named directory and all subdirectories, and /c specifies that the operation continues on all file errors, although the error messages will still be displayed. You can also use the fsutil command, as follows:

fsutil file findbysid savilltech\john d:\documents