Can't download update of NIS - not a valid Win-32 application

"Nathan" suggested I upgrade my NIS software to fix a persistent LU1840 error.

The software offered was NIS 2011.

I fetched the product identification software - no problem.

I ran it - no problem.

I fetched NISDownload.exe - no problem.

I tried to run it. Windows XP announced that it is "not a valid Win-32 application".

HELP!!!