hmm maybe you can view the "event viewer" in vista and see what happened when you disconnected

http://windowshelp.microsoft.com/Win...ef9da1033.mspx

maybe your drivers for the network card is corrupted or something. event viewer will also tell the times and date of when an error occured or a application stopped working. this way you can log into wow and when you get disconnected look at the time and check event viewer for the same time and date. this way you can pinpoint the problem(if it is not hardware related)