I am using Endnote on Vista 64bit together with word 2007.
The problem:
Since I started using endnote, with word, my computer was allmost at a standstill, for no reason.
Solution:
1) Use the build in update function to get your Endnote copy to 2.02
2) Install a 64bit patch from Endnote, see http://www.endnote.com/support/Faqs/Install/faq28.asp