DSI presets are generally intended to demo an instrument's capabilities. They tend to be overly busy, so as to impress the listener. They are often not that musically useable.
If you go to program 128, Bank 1, you'll find a very plain sound from which you can begin designing your own sounds. The Prophet '08 offers triangle, sawtooth, triangle-sawtooth, and pulse waveforms. A square wave is achieved by setting the pulse at "48". A basic sine waveform is achieved either by using a triangle waveform and trimming back the cut off frequency, or else, by turning up the resonance all the way in 4-pole mode and adjusting the frequency and Keyboard Amount. But before trying this, do make sure you've turned the volume down to a minimum, or you'll blow your speakers and your ear drums!
I would suggest experimenting with the 2-pole filter setting with the resonance up all the way; this creates some smooth and Oberheim-ish filter sweeps and static settings. Also, the ability to layer two sounds means that only your creativity is the limit. Combining two contrasting sounds - such as one with a slow attack and the other with a fast attack - can create wonderful effects. Also, don't forget to experiment with the B Output option on the back of the instrument. This allows you either to pan each layer for rich stereo depth, or else, to process them differently. Again, combining sounds with contrasts is very effective. For example, you could have only a touch of reverb on one sound and an immense amount of reverb on the other sound combined with a slight delay from the envelope. This creates an ethereal echo. There is just so much musical potential in the Prophet '08. Enjoy, experiment, and be musical with it!