Windows Vista users complain about complete operating system crashs resulting in blue screens. iTunes 8 for Windows seems to have the following issues, when using under Vista:

• after connection an iPod Touch or an iPhone to the USB port: complete system hang up
• CD/DVD drives disappear from Windows Explorer

But Apple already reacted and distributes now a fixed version. This implies you need to uninstall your current iTunes 8, then download the fixed iTunes 8 and install ii.