"To determine which service pack is currently installed on your computer, follow these steps:
1. Click Start, and then click Run.
2. Copy and paste, or type the following command and then click OK:
winver
A dialog box displays the version of Windows and the service pack that is currently installed on your computer."
So what do you suggest I do now? I can't find much on SP4 except download it, won't. Don't see any known issues.
More modern (present-time) MS updates from that point on, haven't been any trouble for me...known bugs have been found and eliminated, I take it.