Dapper probably setup a few screen resolutions, with one as the default. You can cycle through the settings (and hopefully find one kinder to your eyes) with:
ctrl+alt+numpad+ or ctrl+alt+numpad- (that's control + alt + [numpad minus sign] or control + alt +[numpad + sign] to try the various settings).
I don't know enough about Ubuntu to know what other tools are provided to change screen resolution. The hardware detection programs determine the resolutions your monitor are capable of. Then the config files are written. That's where the ctrl+alt+[numpad+ or -] comes in; to cycle through the resolutions set by the hardware config during installation.