Cannot install WGA Plugin

I seem to be having various problems with this pesky 'Windows Genuine
Advantage' stuff. So, amongst other things, I went to this page
http://www.microsoft.com/Genuine/dia...7-1a33ce87cd74
and did its diagnostic check. It opened this page
http://www.microsoft.com/Genuine/dia...ci,cd,cv&cnt=1
and said that my configuration failed in two respects:
Failed: Microsoft Genuine Advantage plugins are installed and loaded
Failed: Microsoft Genuine Advantage plug-ins connect with Microsoft
validation servers

So I clicked 'Resolve now' which downloaded the file
OGAPluginInstall.exe, which is supposed to ensure "...that the
appropriate helper applications, such as the Genuine Advantage Plug-in
for Firefox, is installed."

But on running this as instructed, I got "Installation information
data unavailable." Dead end. Can anyone please advise what I should do
now please?

I don't know whether this is a related issue, but today for the first
time I have just had a message appear in my system tray (on a 'star'
icon, which I think is the WGA thing) saying "This version of Windows
XP is no longer secure."

Note that I still have XP SP1, and don't want to update to SP2 at
present. Partly because I had problems when I did so a year ago, but
also because I will be upgrading my PC in a few months.

Hope someone here can help please.

--
Terry, West Sussex