//   I purchased an xbox 360 primarily to use as a media extender for my pc. I now feel swindled. I tried to connect via the simple instructions to my vista home premium pc. It did not work. neither windows media center can find the extender nor can the xbox find the pc. the xbox does appear on the pc network map.
 I disabled the antivirus and firewall, shared all the folders and files, insured windows media player 11 was installed, insured I had the latest network driver, rebooted the pc and xbox several times, tried connecting via the 8 digit code xbox generates, tried linking the xbox and pc together via a hub, disabled all security software (mcafee), insured I join xbox live, went to the root console and deleted the windows media certificate, insured the correct services were started..........lets just say I exhausted 40 plus options of articles in the support knowledge base. 
I then called xbox tech support and was lied to, hung up on (7 times) and treated like I was a tech idiot. I have to say that it was the worst tech support I had ever received and Microsoft should be embarrassed to be providing that level of service.  What is even more surprising is that most xbox techs told me over and over again that they didn't know vista.
I contacted vista support and was told that they would not assist on an xbox issue.
From reviewing other forums this problem appears not to be unique.
I now can't return the item since the store I purchased the item at is going out of business and stated they no longer would take returns.
I have a hp pavillion running vista home premium sp1, I am using a linksys n class wireless router.
If anyone has any suggestions on how to get the xbox up and functional I would be grateful. Other than that I would have to say I learned an expensive lesson and will try to stay away from any future Microsoft products if possible.

Is you VMC machine connected to your network using a wireless or a wired conection?  If it is wireless, this may be your problem...

I started wireless, then went to a wired connection, then a direct connection via a cross link, then a wired connection via a hub with no router.......... there was no difference.......no connection.

have you seen this thead?  Might help, lots of information - a lot of information.  Last post seems promising, since it was in 2009.

http://thegreenbutton.com/forums/thread/186935.aspx

 

thanks for the link. I now have the xbox seeing my vista pc...but I still cannot enable windows media center extender. the event log is now listing a successful configuration upon entering the 8 digit code. this is incorrect since the process does not move past finding extender and then stating that extender not found. from the xbox the windows media center does not launch. in addition I have had to somewhat cripple my pc ( no firewall or antivirus, no itunes, no tivo desktop, no basic windows security)...removing google picasso helped greatly...but didnt solve the problem.

Yikes, that sounds painful. I have that same setup, but still have AV, Tivo Desktop(which I replaced with pytivo) itunes, and many other things and I can still connect. One thing I did do was turn of UAC on the Vista machine. I know it a security hole, but really my Media PC is just that, I use it for media, not for surfing the web, thats what my laptops are for.

Problem solved!!!!!! sharing issues re files, selective start up via msconfig...

So, my problem sounds identical to yours. What were the sharing issues that you found in selective startup and how did you correct them?

thanks,

GB