I am adding drums from my machine to an existing song thru midi and currently simply throw down a track and then move it into place but I'm sure there is a way to have the song trigger the 880 to start or vis versa.
Where do I look for this info?

The DR880 default for midi setup is auto (will listen for start/stop and also chase to the correct bar).

You will need to just setup Sonar : preference - project - MIDI :
check Transmit MIDI start/cont/stop clock
check Transmit MIDI song position pointer

When you press play/rec in Sonar, your DR880 should begin to playback in sync.

Is this what you're after ?

Assuming you have a midi cable connecting the DR880 to your workstation, there are only two further steps to take:
1. Set the DR880 to sync to an external clock.  If you haven't messed with the defaults, the 880 clock setting should be in 'Auto' mode already. Good to go on that end.
2. In Sonar, enter the Project-->Midi tab of the Preferences and set the appropriate options under 'Send Midi Sync' (check the box next to 'transmit midi start/continue/stop/clock, and be sure to select the appropriate output port).

Done.

Cool, thanks guys.
Glenn

Question: I'm using the DR880 as well, how do you get the same drum sounds recorded that are on the DR880? Is there a specific drum map your using?

I'm using Sonar's TTS-1 for the sounds at this point. But it's a good point.
It is easy to record the audio thru the RCA master out tho. I've been doing that until now.
Someone else may have an idea how do use the 880 sounds as a MIDI synth source tho.

yup, i've done the RCA/edit trick too but it would be nice if they played together in the box. The dr880 is a Roland product which is the parent company of sonar right? You would think that there would be a specific drum map for their specific products.

Point taken.
I originally only wanted MIDI input so that I could get the nice samples on the 880 broken into individual tracks instead of just stereo mix.
I am happy to have at least some options for mixing. 
I assume I can now use any soft synth samples and that would be huge. 

You would think with MIDI in and out that one could use it as a plug-in, tho I have no idea.
Perhaps another thread on that?