Ok, for thoese of you who dont know, I work exclusivly with xbox/nullsoft streaming and this is what I have discovered is the best solution for view streams.
1) Spend $5 on www.ess.tv (Suscriblers currently get access to 46 streams with various forms of entertainment. Check out the ESS streams in WinAmp under ShoutcastTV for listings)
2) Now open up WinAmp (version 5.0+) and select one of the ESS streams and queue that stream in the playlist. Now save that one item playlist as a .pls file and do this to any other streams that you may want to add.
3) For this step your going to need to startup XBMC and connect to the web browser interface. To do this, just enter your xbox's ip into a browser (firefox/ie).
On the left hand side you will see under the "My Pictures" and "My Videos" a set of square icons. The last on the right is "Config", click on it.
On the next screen, click on the text that says "XBMC Options".
Now where it currently says "Video Extensions" go ahead an add .pls to that list.
4) Either FTP over the files or open them using your SMB connection and BAM!
NOTE: For ESS, I find that I can drop the buffer to 756kb a second and get almost instant load time and perfect performance.