I got all the major Windows updates on mine (I think including .Net). While .Net isn't needed for security, I definitely would make sure to get all the MS security updates if you ever plan on having an Internet connection with it.
I'm using the long press right click functionality, and it doesn't seem to hurt SD at all (though it is annoying when you are trying to drag a slider a long way in Windows, or hold down an elevator scroll control button).
There is a fix for the search problem - you just need to add a registry value. See this page: http://support.microsoft.com/?kbid=816665
(SD guys, you really should put that in a FAQ and fix it in the next SD image. It will affect a lot of people.)