jumpy videos

Hi
I am new to flash media server and I am having problems.
I have installed flash media interactive server on my home pc (windows vista ultimate 64bit) I have also installed media server on windows 2003 server which my friend kindly set up for me on his server.
I have practised using VOD service on the streaming server using the flv extension; I have used Action Script 3.0 to stream a H.264 video files with various buffer sizes. The videos show up no problem from both windows vista and windows 2003 server, but the problem I am having is that the playback stops and starts and is very choppy. I thought that flash media server was supposed to prevent all of that. I have tried everything I can think of to get the videos to flow smoothly but I can’t seem to figure it out. I am obviously missing something somewhere, as I get the same results from both vista and win 2000 server.
So I am looking for some clever guy that knows how to get this thing racing for me.

Here is my links for you to test
Link form meda server on winvista
link from medias server on windows2000 server
Appreciate any help from you guys.

Thanks in advance