If you need to re-install a 'hidden' Windows component, eg. outlook express or messenger, there is an easy way to do this... [but you will have to BE CAREFUL!]

1. Open the INF folder in your windows folder [C:\WINDOWS\INF]
2. Find the *.inf files [view>arrange icons by>type]
3. Find the application title you need in the filename [for example messenger is msmsgs.inf] If you are unsure of the installer, RIGHT CLICK on the file, then select open, at the top of the file should say what application it is:
   
   ; MSMSGS.INF
   ; Setup INF file for Messenger
   
4. When you have found the file the right click on it then click install.

Tip:  To reinstall Microsoft Outlook Express, Right click and select install on MSOE50.inf