Use "Line in sampling" from the File menu. Youll have to open the audio mixer using the button that Audiograbber provides, or double-click on the speaker icon in your system tray (it doesnt always open from Autobiographer), select properties from the Options menu, then click on recording (or drop down the menu to select the audio input if the radio buttons are grayed out).
Some computers will allow you to select the Stereo Mix as the recording input -- this is what you want. It all depends on the audio driver and what it exposes to Windows.
Otherwise you can use a splitter cable from the line/speaker output to go to both your speakers and loopback to your line-in and record that. If you do that, you will have to mute the Line-In on the playback mixer or you will get terrible sounds...
Youll have to adjust the audio levels of both the playback and record to get a get level. You want it to be in the middle most of the time, with a few peaks up to 90-95%, but never over 99% or you will get distortion. I tend to keep the playback level as high as possible and the record level as low as possible to give the best recording level -- this gives the lowest noise levels.