If you have this problem, the following might save you an hour with tech support:
Peachtree accounting 2009 would not upgrade or install on a recently upgraded XP sp2 computer, it always failed during the pervasive database section. The support tech from sagesoftware confirmed that the version of windows installer 3.0 needed upgraded to 3.1. This file is called msiexec.exe and is buried in the system32 folder. Right click on it, click properties, click the version tab. An upgrade can be found on microsoft's download website. I noticed that a new computer that came loaded with XP sp2 already had the 3.1 version, so evidently the one upgraded from windows 2000 to XP did not get the newest version.

