It's the same as OS9 days really. Pop the Tiger DVD into the drive, restart while holding down the C key. When the system comes up, go through the menus at the top of the screen until you find Disk Utility. It's there, trust me, it just defaults to the installer screen. Run Disk Utility to repair the disk, then quit Disk Utility. Then quit the installer, and it will ask you if you want to restart and click yes. If I've missed some details, that's kindof the outline of the whole procedure. The only thing your intuition was missing was that the Disk Utility application is hidden in a menu upon restarting booted from the Tiger DVD.