I use WIN 7/64 bit and Sonar X2 Producer, and play the Addictive Keys instrument. WHen I press a key, I realize
the latency in triggering the note is somewhat unavoidable, but I wonder if there's a way to improve the
latency?
 
I play into a FocusRite audio device with Firewire and ASIO, so the settings seem to be hardwired, and not adjustable on the FocusRite side of things, so I don't know what or if I can tweak on the PC side.
 
Any advice, or what I should read?
 
THanks for any help!
COrey

What is your ASIO latency set at in the Preferences?
Some can go down to 2 ms roundtrip, but around 4-6 ms is already very good and inaudible. It depends on your computer and the VSTs you use. For example VSTs with a look-ahead-function obviously create more latency than some others.
Below 20 ms roundtrip latency is somewhat tolerable, if you're not working on very intensive material, but it's far too
high for rapid, accurate passages etc.

On the Focusrite you can go into MixControl and, under <Settings> change the number of buffers. It gets dodgy for most systems under 256...that will generally get you under 20 msec. High powered computers with 8GB RAM can go down to 64 or even 32. 
 
I have mostly given up on tracking with Virtual MIDI. I listen live on my keyboard voice, but record both the MIDI output and the keyboard output. This gives me flexibility later to voice substitute or just use the recorded voice out (my NORD has decent voices). I can't wait to record from my Fender/Rhodes Mark I live and use Melodyne to extract MIDI and layer, but haven't had enough time with X3 and Melodyne yet (I did do the optional upgrade though). 
 
Sorry to ramble...key point is to expreiment with buffer size on the Focusrite...I have a Saffire PRO 40.

THanks so very much for the responses. I'm glad you mentioned changing the ASIO buffer size in the mixing GUI - I needed to be reminded of that. I was at 512, which meant latency was 11ms, but once I knocked it down to 128, it shrunk to 2.9MS.
 
I'll experiment to find the best buffer size. Again, thanks so much!!!!

When you're processing a plugin instrument you need to have smaller sized buffers. When mixing you can raise them again.

This is a normal part of using a DAW.

You could also benefit massively when tracking/recording, simply by globally bypassing all Fx (press 'E')

shmuelyosef
On the Focusrite you can go into MixControl and, under <Settings> change the number of buffers. It gets dodgy for most systems under 256...that will generally get you under 20 msec. High powered computers with 8GB RAM can go down to 64 or even 32. 
 
I have mostly given up on tracking with Virtual MIDI. I listen live on my keyboard voice, but record both the MIDI output and the keyboard output. This gives me flexibility later to voice substitute or just use the recorded voice out (my NORD has decent voices). I can't wait to record from my Fender/Rhodes Mark I live and use Melodyne to extract MIDI and layer, but haven't had enough time with X3 and Melodyne yet (I did do the optional upgrade though). 
 
Sorry to ramble...key point is to expreiment with buffer size on the Focusrite...I have a Saffire PRO 40.

Please don't apologize after such a helpful answer! :-)

I routinely go into Preferences | Drivers | ASIO Panel and set it low (like 128) while tracking.  Then I reset it back to 1024 when mixing.
 
It is an extra step but with a low setting you get almost no delay.  With the high setting you avoid crackles and drop outs that can happen at lower settings.