Like the others on this post, since installing 3.2-1922, streaming music from the NAS to the Airport Express directly via attached Mac Pro or wirelessly via the PowerBook Pro would cause the stream to stutter at some point and prove impossible to use.
This morning I upgraded my DSM to 3.2-1944, which was released yesterday. I've been streaming from the Mac Pro for the better part of two hours with absolutely no problems! It would appear that the stability we had with DSM 3.1 has returned.
Anyway, just wanted to impart some good news, and I hope you find your experience to be the same.
Disk Station DS410 | Mac Pro 3,1 | 10.6.8