Today I had a few minutes, so I tried stopping all the SQL Server processes and running the patch manually using the version downloaded from the knowledge base. Still no go.
I also tried using the add-remove programs suggestion the patch log suggests, but after you get part way through it, it starts asking for SQLRUN_SQL.MSI which is not on the computer. Nor is it on the ACT 2009 install CD. And to make matters worse, I couldn't find it in the developer downloads area in MSDN.
So now I'm at an impasse. I guess the next step is to see if Peachtree (Sage) has a fix for this. I'm not holding my breath.
Oh and one comment suggested looking for another instance of SQL Server on the machine. I haven't found one yet.