So avid drummer here, just got some electric drums so i can practice in the apartment. I wanted to record some stuff to send to family members etc, which is one of the advantages of having the electric kit. Downloaded audacity, everything was good to go. Im using the aux out analog to the aux in mic port in the pc. This is on Windows 7 btw. I got the 1/4 to 1/8 adaptor to plug in the back of the drum brain. I changed the port in on the audacity software. It does record, however after a few seconds the playback sound of the drums on the pc, when i hit play, sounds like the drums are underwater and sound horrible. What am I missing here? I did have headphones plugged into the drum brain so I could hear myself as I played. I thought maybe that was the problem, so I unplugged them and went “dry”. Still did the same thing. Now I do think I remember the salesman at the Radio Shack that i got the convertor from, said something about it being digital maybe? Im not quite sure. Are there diff types of 1/4 to 1/8 convertors? I may just be imagining this though! 
You may have two problems. The computer thinks your drum playing is interference and you can’t use the Mic-In for what you’re doing.
http://manual.audacityteam.org/o/man/faq_recording_troubleshooting.html#enhancements
Mic-In is used for microphones.
http://kozco.com/tech/audacity/pix/computerAnalogMicrophone.jpg
Anything more powerful than that needs a stereo to USB adapter such as the UCA-202 that I use.
http://www.kozco.com/tech/audacity/pix/peaveyUCA202Lenovo.jpg
Both of those should turn your computer into a straight stereo sound recorder. The Behringer UCA202 in the illustration is one of the three hardware devices we certified for overdubbing/sound-on-sound.
http://manual.audacityteam.org/o/man/tutorial_recording_multi_track_overdubs.html
Koz
Ok thanks. Ill check when I get home. I thought it was aux in, with the microphone icon next to it. Ill have to look. And mess with the settings some.