Microsoft Security Essentials

While I have been satisfied with products such as Spybot and Clamwin, Microsoft Security Essentials is free and may be worth a look.

Microsoft Security Essentials provides real-time protection for your home PC that guards against viruses, spyware, and other malicious software.

Windows Upgrade Stopped By DEP

While applying Microsoft's patches to a MS Windows Vista installating, the installer was stopped by Data Execution Prevention.

A screenshot was able to capture most of the message.

Faster Vista Booting

Press the start button and in the "Start Search" box type: msconfig

The "System Configuration" utility will run.

Choose the "Boot" tab.
Check "No GUI Boot". This will disable the splash screen during startup.

Click the "Advanced options..." button.
Check "Number of processors", and choose the highest number. This will allow multi-core (multi-CPU) processing during startup.