SS2005 Express Edition SP4 Upgrade Question

Hi.  Perhaps you can help reduce my confusion.  I have a vendor package that incorporates SS2005 Express, currently at SP1.  Our security manager informed me I have to install updates MS08-040 and MS09-004 to close a security gap.  I decided to simply upgrade from SP1 to SP4.  When I attempt to run the SP4 executable, it seems like I get a successful completion.  To make sure everything is good, I restarted the processor.

The problem comes when I issue SELECT @@Version.  It returns that I am at "Build 7601: Service Pack 1".  However, when I run the following:

  SELECT CONVERT(char(15), SERVERPROPERTY('ProductLevel')) AS 'ProductLevel'

  SELECT CONVERT(char(30), SERVERPROPERTY('ProductVersion')) AS 'ProductVersion'

It says my Product Level is at SP4.  the Product Version says 9.00.5000.00.

Which is correct, SP1 or SP4????  If SP4 is correct, any idea why @@Version would not pick that up?

Thanks in advance.

Jim Drewe