Set Automatic Updates to download only

By default, Windows Vista will automatically download and install any patches and updates that Microsoft considers crucial. This will often result in an automatic operating system restart, which can be canceled if you are at the keyboard, but it can play havoc with your torrent downloading if you are not.

A better way to do things is to have Vista download the patches automatically, but wait for your permission to install them and restart the computer.

To enable manual update installation:

Go to 'start/control panel/security/turn automatic updating on or off'
Select the 'download updates but let me choose whether to install them' option.

Click 'OK'

Windows Vista will now notify you when updates are available via an icon in the taskbar, but will not install them until told to. When you do choose to install the patches, you'll have the opportunity of scanning over the patches and deselecting any you feel are unnecessary.