If you are thinking of buying Word 2011 for your Mac, you should be aware that EndNote will not work with it.
EndNote works with Word 2008 for Mac without difficulties, but it will not work with the 2011 version.
Also, EndNote does not work with the 64 Bit version of Word for Windows computers. If you are purchasing new software, choose the 32 bit version. The salesperson may tell you the 64 bit version is better, but it doesn't work with many plug-ins and add-ins (including EndNote's Cite While You Write).
For more information, see this page: