what are you trying to stream to your XBox. I have a DIR-825 and stream lots of video to my XBox and it doesn't stutter.
If you are in a wireless congested area, you might try changing your radio channel, most routers default to the same channel.
I have a Linksys dual band ethernet bridge and have it set to the 5 Ghz band. On the output of the bridge, I have a small 5 port ethernet switch. I have my XBox, my desktop computer, my Dish Network receiver, and a NAS drive all connected to the switch.
In fact, last night, my wife was watching a movie from our Windows Home Server via the XBox. I got on my computer and watched the same movie on my computer. Neither of the movies stuttered or rebuffered, the TV or the Computer.