This software cannot be installed on this computer.
In Finder (i.e. click on your desktop background or the two tone blue face in your Dock), go to the "Go" menu, and select "Go to Folder…" (or hold Shift and Command and type "g"), then type in "/Volumes/Mac OS X Install Disc 1/System/Installation/Packages", then double-click "Bundled Software.mpkg"; but, the same check (where you might get the alert "This software cannot be installed on this computer.") still applies as clicking the shortcut on the disk (i.e. when you put in the disk (or double-click the "Mac OS X Install Disc 1" DVD icon on your desktop), a popup window appears with a shortcut "Install Bundled Software Only".
If you know this is the specific install disk that came with your specific computer, there's a chance the .dist file could be corrupt. Make a disk image (Go menu, Utilities, Disk Utility: select the Install Disc on the left, then click the New Image button and just click Save--should place on your desktop), then edit that .mpkg file (i.e. Go to Folder, but replace "/Volumes/" with "~/Desktop/" from above directions), then right-click (or hold the Control key and click) on the .mpkg and select "Show Package Contents", then double-click on "Contents", then right-click on "Bundled Software.dist" and hover over "Open With" and select "Other…", then scroll down and select "TextEdit" and click the Open button. Then in TextEdit, go to the "Edit" menu, hover over "Find" and select "Find…" (or hold the Command key and type "f"), then type "var hwbeSupportedMachines" (note: this has changed slightly over the years, so perhaps just a "Machines" and use your cognitive skills) and click the Next button, which should take you to the line you need to edit. In the apple menu (i.e. apple icon in the upper left of your screen), select "About This Mac", then click the More Info… button, then look at the "Model Identifier:" and note what's to the right of it (e.g. "Macmini3,1"). This is where you will probably see a difference; go ahead and fix the typo (or just add ",'Macmini3,1'" inside the brackets), close the TextEdit window and click Save when prompted. Then right-click on that .dmg (Install Disc) and select "Burn "Mac OS X Install Disc 1" to Disc...".
Or really, just get into that second disk (in the hidden "Packages" folder), and double-click on any .pkg file to install the individual component; or, in the case of an .mpkg (e.g. iPhoto), show package contents, and in the Content/Installers folder, double-click iPhoto.pkg (and iPhotoContent.pkg); note: you may need iLifeMediaBrowser.pkg and iLifeCookie.pkg, back in the Packages folder (and may need to have 10.4.7, not 10.4.11); otherwise, just copy the iPhoto.app from someone else, and only run the iLifeMediaBrowser.pkg and iLifeCookie.pkg installers.