Back in what has to qualify as the computer stone age, a high school Biology teacher I worked with got a bunch of A/D converters and wired them to his networked C-64s, I wrote the software myself. We were measuring the acceleration of gravity (okay, not a Biology experiment, but he saw it in a magazine and wanted to try it himself) and graphing student's heartbeats and so on - in 1986. So really, the oscilloscope part is trivial. Might even be able to use the existing A/D and DSP from the sound card, if you can figure out how to feed your signal to the Mic. input. (Yes, 1986 - the school board wanted him to upgrade to PC XTs, he preferred to use what he had. When they saw what we did with those old C-64s, all they could do was scratch their heads.)