Well Now a days you get those usb soundcards extremely cheap around 1-2$ .So why not convert them into oscilloscope.You might be thinking to use integrated sound card on your mother board,which you make wreck during process and plus if you want to see dc impulses on computer you may have to desolder some capacitors on PCB which you cant on integrated sound cards.
So go on buy an usb sound card and download a software named miniscope to convert it into low slow but accurate oscilloscope with less money.
Well in soundcard you got to remove electrolytic DC capacitors on left and right channel.So you get 3 wires
1. Ground 5. left input(probe 1) 2.right input(probe 2)
Check this post to learn more.CLick here
Then try connecting and using it usually china products to save money dont use electrolytic capacitors on board.
If still any problem arise then go to link mentioned above and read in dept debugging guide.
Hope there are no problem.Let the power of oscilloscope be in palms of your hands!