Jamcast

Okay getting really frustrated. All Vista and Windows 7 boxes have no problem with Jamcast and Jamcast is even installed on Windows XP Pro SP3 as my quote unquote server. However I can not get a single XP Box to actually get the UPNP icon for it to configure to JamCast. I have made sure that UPNP User Interface is installed as well as the Internet Gateway Device Discovery. I have made sure the SSDP Service is running. I can even run Test software from the Server that sees the clients, and the clients are seeing the Server. But the actual discovery and configuration necessary never occurs. Attempted reboots, 20 minute and 30 minute waits, and even made sure UPNP was turned on in my router (seems to be a big deal according to some) and everything I can think of. While there is too much information and various papers written on UPNP on the web, it still seems to be a magic black box that either works if you hold your toes right or doesn't, nothing really tells you how to fix it. In my trials of other software mainly Tversity, it had no problem with all machines..popped right up and consistently over and over. So what is the difference in their discovery and identification vs. Jamcast? I have seen that there are various SDK's written for UPNP access. Is a difference in implementation the reason? What is so different between UPNP in Vista and Windows 7 and XP? Must be something. It just works every time with Vista and 7 but not one single XP box yet? Anybody have any suggestions? Thanks!