If you have a Win2k or WinXP install, you might consider removing Outlook Express, because it's a big security hole. Unfortunately, MS decided you really need MSOE, and attempting to delete the exe file will cause the exe file to reappear.

Here's a lengthy how-to about disabling msoe.

http://articles.techrepublic.com.com/5100-10877_11-5551863.html

Newsflash: I feel stupid now. The real way to remove it is to go into Add/Remove Programs, click on the Configure Components icon, and then uncheck the OE option. You can also disable Windows Messenger and MSN Explorer.