Have you had a look on the Sage web site? Your problem could be ME. for example - Sage Instant Accounts click here 'This product will not install or run on the Microsoft Windows 95, Windows 98, Windows ME, or Windows NT4 operating systems.'
Yes - If you are running Microsoft Windows 2000, Me, 98 or 95, it is strongly recommended that you upgrade to the latest version of Microsoft Windows Installer. If needed there is a link to M'soft Win Installer within that link.
My sincere apologies if I have given you wrong information - not being familiar with Sage software, I assumed that if it had asked for Service Pack3 for ME (I know there is no such thing) then there must be a reason for the software's request. So the nearest thing to that is the link I gave - perhaps someone else can explain the software's request ... ßeta, perhaps you can explain it?