As I said before the quickest thing to do is back up data on computer, wipe vista install xp, then install vista (dual boot) install shoutcast or SAM on XP.
If you have vista and a laptop you wont stand a chance to dj with SAM as the soundcounds they use are utter shit if its a soundmax etc.
The trial version 4 is ment to work on vista anything below version4 your just wasting your time.
The whole way vista does sound is totally different to xp until there is a new shoucast dsp that was built for Vista I suggest you downgrade to xp (dual boot)
check this link out. your notice that some people say sam works fine and so will shoutcast on vista if your only streaming music with no dj voice.
If you try to use mic and music at the same time on vista you cant, you can do either one or the other not both sand this is due to the microsoft mix map for sound gone out of vista.
http://support.spacialaudio.com/forums/
viewtopic.php?t=20654&highlight=vista