Ok, Im trying to use Camtasia Studio 3.1.2

Everything is fine except it will not let me record any audio unless I hook up a microphone (which i would rather not do due to quality)

When I run the program it says its unable to automatically detect my audio.

Im using an up to date Toshiba laptop with Realtek HD audio.
WinXP Duo Core blah blah

Someone Help PLEASE!!! i cant find any info anywhere!!