<p>I installed both the Delphi 2009 trial and actual release via the web installer when I received them and experienced the same errors when installing both.</p>

<p>Both times it appears that the core web installer failed when it went to spawn the additional install packages for boost, documentation and dbtools.  (It brought up a findfile dialog asking for a setup.msi that didn't exist on my machine).  When cancelling out of this, the installer reported a fatal error.</p>

<p>The uninstaller did not appear in my program list, and would did not launch from the installation folder.</p>

<p>Future attempts to bring up the installer had it in a state where it thought Delphi 2009 was already installed and it wouldn't correct or repair or uninstall it.</p>

The problems seem to originate with the web installer not having all the files needed.
Download the 2009 ISO:
http://cc.codegear.com/item/26049
Mounted it using this free tool from Microsoft:
http://download.microsoft.com/download/7/b/6/7b6abd84-7841-4978-96f5-bd58df02efa2/winxpvirtualcdcontrolpanel_21.exe
(You can burn it to a DVD too)
Then reran the installer.  At this point, both the repair and uninstall worked.