I am deploying in XLA using Nullsoft Installer (NSIS).

I was thinking of just adding the XLA to :
%APPDATA%\Microsoft\Excel\XLSTART

This is the Adobe Acrobat 6 appears to install PDFMaker.xla.
I think the path to XLStart is different on Vista.

What is my best bet for an automatic installation on different Windows NT
based OSs (2000,2003,XP,Vista)
for users with different versions of Office (2000-2007) ?

Thanks a bunch !
Jj