I need to add wireless capability to my DAW, and the wireless will probably remain on all the time. Is there an advantage to PCI wireless card over a USB?  I know each may have some possible negative effects, but any advice here is welcome.

Also, if it matters, the interface on this DAW will be a PCI based Echo Gina 3G, and the only other USB device will be a Midi keyboard.

An active wireless is notorious for causing DPC latency problems. Why does it need to be on all the time? It may be more convenient to disable the wireless while doing audio processing by just unplugging the USB.

Its not for me, and I am assuming (correctly) that the person using it will be too lazy to spend 3 seconds disabling it while recording.  SOOO, I have to just try to negate as much of the byproduct as possible by choosing the right one.  Any ideas if there is a significant difference between PCI and USB?

Wi-Fi as previously noted is well known for causing DPC latency problems (which translates to audio problems including clicks, pops, etc).  The computer forums are loaded with people reporting these problems.
 
There are wireless keyboards, if its for control, that work without causing problems.   

sven450
Its not for me, and I am assuming (correctly) that the person using it will be too lazy to spend 3 seconds disabling it while recording.  SOOO, I have to just try to negate as much of the byproduct as possible by choosing the right one.  Any ideas if there is a significant difference between PCI and USB?

Of course there are differences, but, if you are going wireless, you have already chosen to decrease your performance on the network enormously. 80211N is 300 Mbs. USB 2 is 480 Mbps. The bottleneck is not how you connect to the computer, it is how you connect to the network. If you want good network performance hard wire to your router. 

I have 2 different USB wireless devices, one was $30,  the new one was only $12, They both work fine but  for my DAW I like the fact that the $30 one came with a USB extension and a little docking station. So it sits on my desk and I can unplug it. The cheapo one is on a old Laptop that used an express slot device that I couldn't find drivers for anymore. 

Got it.  I'll try to convince him of the need to unhook/disconnect when playing on the DAW.  

If you're going wireless, also consider 802.11ac rather than 802.11n. In this setup, you'll need a 802.11ac router as well as an AC adapter to get the optimized AC speed. 
 
http://www.extremetech.com/computing/160837-what-is-802-11ac-and-how-much-faster-than-802-11n-is-it
 
http://www.pcmag.com/article2/0,2817,2417341,00.asp
 
I do have the ASUS ac router pictured in the first article (the first one), and also have the Edimax adapter..........both work extremely well together.
 
The adapter is of course is hooked up to my non-daw home PC.

Mesh
If you're going wireless, also consider 802.11ac rather than 802.11n. In this setup, you'll need a 802.11ac router as well as an AC adapter to get the optimized AC speed. 
 
http://www.extremetech.com/computing/160837-what-is-802-11ac-and-how-much-faster-than-802-11n-is-it
 
http://www.pcmag.com/article2/0,2817,2417341,00.asp
 
I do have the ASUS ac router pictured in the first article (the first one), and also have the Edimax adapter..........both work extremely well together.
 
The adapter is of course is hooked up to my non-daw home PC.

Interesting.  I'll look into it.