I wonder if the sites are down or something. I've used pocketpcmedia in the past with hardly any problems since I switched to verizon wireless EV-DO network. Before that when I used t-mobile I would get a lot of buffering issues so it would play for awhile then stop and WMP would report buffering and back and forth. NOw I hardly ever see that message once a file starts streaming. Try this site. I listen to WBZ Radio every morning on my way to work by using a url from this site
http://www.radio4pda.com/ .
For WMP there's not much you can do about buffering issues but even though I don't use it I know you can adjust the cache size or something to get GSPlayer to work better.
HTH