Need to upgrade to some better sound for my 600m, the staticy headphone output just isn't cutting it anymore.

I'm looking at the Creative SoundBlaster Extigy and Audigy 2 NX. Both are external USB-connected 5.1 soundcards.

 

Audigy 2 NX:

http://soundblaster.com/products/audigy2nx/welcome.asp

 

Extigy:

http://soundblaster.com/products/extigy/

 

I can get both for basically the same price. The Audigy 2 NX seems to be a LOT better: USB 2.0, 7.1 support, smaller, etc. It is also much newer.

Am I missing some critical difference between these two? Any recommendations are welcome as well.