The dbx files typically are in Documents and Settings/username/local
settings/applications data/identities..... but you can right click on your
Inbox and select properties to display the exact path. The History folder
is nearby in Documents and Settings/username/local settings.
Outlook Express: Open the program and click on Tools> Options> Maintenance>
Store Folders. The window that appears will show you the path to your *.dbx
files.
Temporary Internet Files are stored on a per user basis in a hidden folder:
Documents and Settings\<user>\Local Settings\Temporary Internet Files. You
can use Internet Options> General> TIF> Delete Files or Disk Cleanup to
clear this folder. Click the Delete Cookies button in the same section if
you want to clear those too.