First, are you certain that the first error you encounter mentions "Access to the path ... is denied"? It turns out that there are several Error 1001 messages, and this discussion is about just one of them.
If that's the case, try the following. (The folder name changed after my June 2, 2011 post.)
1. Make sure you are logged in as an administrator.
2. Make sure you have Excel closed.
3. In Windows Explorer, remove this entire folder: "C:\Program Files (x86)\Social Media Research Foundation\NodeXL Excel Template".
4. Run Setup.exe again.