I have 1.8 Ghz quad core pc with vista x64 running wired network lan to xbox 360 extender.  I can stream SD (at around 8 mbps stream rate) to xbox360 but HD (at around 12 mbps stream rate) stutters and barely plays.  Same network and HD file plays fine from the pc to my PS3 (right next to the xbox360).

I only have microsoft firewall and the extender and extender services are on the list to be allowed, still I disabled the firewall and tested and still same result. I made sure I have no other network activity and closed any un-needed apps on the pc.  Network test is immaculate at highest green bars (of course its wired network)

 As I mentioned the HD stream is about 12 mbps streaming rate and the content is 720p mpeg2 file. It plays fine on the pc and also streamed to PS3...its just the xbox 360 extender having issue.  I cant imagine 4 mbps difference causing a  problem and I have streamed  up to 15-18 mbps from pc to ps3 without a hitch

 Any suggestions? 

Ok discovered that Windows Firewall wasnt off actually...turned it off again....retried...it worked then.  I thought that windows firewall wouldnt interfere with media center extender and media center extensibility host entered as an exception.  And why didnt that impact when streaming to the PS3?  Why was only the xbox360 extender affected?