Windows Live OneCare 90-Day Free Trial
All-in-one PC care for people who have other things to think about - Download it

What it is
An automatically self-updating PC care service that’s always on, helping provide persistent protection against viruses, hackers, and other threats, and helping keep your PC tuned up and your important documents backed up.
What it does for you
Installation requirements for Windows Live OneCare
What operating systems are supported?
Windows XP SP2 or Windows Vista (build 5500 or greater; recommended build is 5600 aka RC1)
Can I use Windows Live OneCare with Windows XP or Vista x64 versions?
Not at this time.
What is the “Activate” button in the client?
This is for converting from a free trial to a paid subscription. You can safely ignore the button during the beta.
What if new viruses or other Internet threats come out?
Windows Live OneCare regularly updates itself based on emerging Internet threats so you can have better peace of mind.
What is a PC tune-up, and how is it done?
A PC tune-up is pretty much like a tune-up for your car: a series of maintenance tasks to keep it running at optimum speed and efficiency. After installation, Windows Live OneCare will automatically run your first tune-up at 1:00 a.m., then once every four weeks after that. Tune-ups can take a while, and that’s why they’re scheduled for a time when you most likely won’t be using your computer. But that’s your choice. Tune-ups can be done whenever you want.