Lidgren.Network runs exceptionally well with SGDK2 in terms of online support/networking, and it recieves constant updates.
AFAIK, it only needed 12 lines of code to get a server and client up and connect the two.http://code.google.com/p/lidgren-network/wiki/Quickstart
I guess if you've had experience with Raknet, go for it.
I was wondering about free audio support that allows playback of OGG files. If and when you do discover how to do this, feel free to share.
Tigsource tells me that there's a $500 dollar license with FmodEX- for commercial games. (But who knows about the future of my games?