Reset the machine, Endnote should install itself on startup. Endnote is located in Start -> All Programs -> Endnote -> Endnote Program.
If you cannot find Endnote on your machine, try logging in and resetting. It should appear on startup.
Because this is an automatic installation, it doesn't integrate with Word for each user automatically. You will need to set this up yourself.
To do this, follow these instructions:
Locate the following files in C:\Program Files\EndNote X (you can also download them from here (as a ZIP file))
Copy them to your u:\application data\word\startup (if this folder isn't there, try copying them to c:\Documents and Settings\[your name]\Application Data\Microsoft\Word\Startup\)
Before you use the tools for the first time, close Word, then open EndNote and an EndNote library (if you don't have an Endnote library, create a "dummy" library and save it to your desktop), then re-open Word and click on one of the EndNote tools. The programs must only be opened in this order the first time you use the tools so that Windows will be configured correctly.
If you use MS Office 2007, the Endnote plugin appears under the "Add-Ins" menu.