Bonjour is to windows what rendevous is to Macs.
It scans the network for other iTunes shares.
Here is how to get to disable Bonjour.
Click the start button -->Settings-->Control Panel-->Administrative Tools -->Services
Right click Bonjour - click properties - click on
stop service, then set the startup type to disabled.
The key to fixing my Itunes 5 problem was to uninstall Itunes 5, uninstall quicktime - go into the program files and delete the itunes and quicktime folders (yep despite being uninstalled they were still in the folders) Then I rebooted, got the standalone Quicktime 7 - installed it. Then installed Itunes. Works fine now.
The Quicktime 7 standalone can be downloaded from here:
http://www.apple.com/quicktime/download/standalone.html