Okay...I've finally got all my stuff connected (Sonar 8 studio and Korg Triton Extreme via USB connection). My Korg comes up just fine under "MIDI Devices" and have selected it for IN/OUT. I have also selected the "S.PLAY" button on the Korg. When I open up some of my old MIDI files, it plays them just fine. However, when I try to build a new MIDI (say, 16 channel), it only gives a "Piano" sound for each part played. I have tried switching the keyboard to "SEQ," but it does the same thing. I'm not sure what I'm doing wrong here, and my brain has simply stopped working. Any ideas or suggestions would be greatly appreciated! Thanks! ~Sean

What's not clear is when you say you open your old midi files, is that open in Sonar or open within the Korg? 
Piano is the default MIDI sound when no Program # has been assigned. 
You have to select the sounds for each channel. You can do this in Sonar by using the track properties. 

You can make this a lot easier by getting the instrument file (.INS) for the Triton Extreme. Try here: www.tritonhaven.com

Then you have to go into the Instruments definition section of Sonar (see the Help Menu)

Select Define - Import and point it to the INS file

Then from the main instrument setup screen, map each channel of your MIDI interface to the Triton Extreme. 

If you set it up right, when you select a Bank or a Patch, it should let you select from the list of patches in the INS file. 

Make sure you have the Triton set to multimode so it can play more than one sound at a time. Each different sound has to use a different MIDI channel on the interface. 

This is a must to set up Korg instruments this way since Korg has a really strange bank numbering system.