The Cakewalk TTS-1 has a fiddle patch. Its not great, but like all synthesizer or sampled emulations of instruments, how realistic it sounds depends more on how you play it than the sample being played. Fiddle players use a lot of doublestops (2 notes played at the same time a 4th apart), grace notes, spiccato, bow bouncing, and slides because it is a fretless instrument. It also helps if you use a synth keyboard to play the parts so you can use the pitchbend wheel and the modulation wheel to make it sound more real. Just entering notes into the piano roll view or the staff view is not going to yield good results. If you're not a fiddle player, do some research on the web on fiddle techniques.