Hey zman, nice script!
Haven't tried running it but I know that taskkill is not available for Windows XP *Home* Edition (and probably not for Windows versions before that either). Which means it won't work for most surfers and they'll end up getting a "not a valid Win32 program" - message.
pskill might be an option though it means you'd have to include it in the zip
http://www.sysinternals.com/Utilities/PsKill.html
Also, you might wanna add the "/-p" parameter to your dir commands in case the user has the DIRCMD variable set.