I'm trying to install SP3 on an install of Sql Server 2005 running on Server 2003 32 bit. When I run the installer it doesn't seem to recognize that I have SQL Server 2005 installed. The dialog box that asks what features should be updated doesn't show any by default. More troubling, it doesn't allow me to check any of those boxes to update features like Database Services or Reporting Services.

When I select one of these services, the "Status" box says "Not Valid". The message says something about more recent updates, but Select @@Version gives me this:

Microsoft SQL Server 2005 - 9.00.4053.00 (Intel X86) May 26 2009 14:24:20 Copyright (c) 1988-2005 Microsoft Corporation Standard Edition on Windows NT 5.2 (Build 3790: Service Pack 2)