I have a lightsnake usb connection that goes from my USB, and on the other end is a headphone jack, and a line in. When I record The guitar parts first, then try to add drums to it, everything that is being played is being re-recorded onto the new drum track. I Think that thats just the type of lightsnake that i have, and I have seen the usb-to-1/4 inch plug, and it is also a lightsnake, but i am wondering if i need to buy that instead of what i have right now.
You’re on a Windows machine, right? Windows has a setting (sometimes called Mix-Out) where it tries to record the whole world in addition to your show. You should probably turn that off.
Windows Control Panel
http://audacityteam.org/wiki/index.php?title=Mixer_Toolbar_Issues#Using_the_Control_Panel
Koz