Realtime Signal Processing for Unix?

Christoph Zrenner asks: "I'm a UK medical student with a serious research interest in "how to interface neurons with computers". We do a major project in our third year and I'm interfacing an eel spinal cord (8 analog inputs, 12 analog outputs) to simulate the eel's movements on a computer. The processing needs to happen in real-time (1ms delay) so that the cord can get feedback from the computer. Having spent two days foraging through the Internet I still haven't come up with a decent solution - does anyone have any experience with this kind of thing? I was hoping to use the Matlab/Linux combination but only found an (expensive!) Realtime Windows Target Toolkit for Matlab!"