Please, please stay away from Advanced System Care. You want to keep a clean mean computer, that good. We do understand. Because you are using Windows 7 now all those tweaks we use to do are not necessary. Windows 7 doesn't want or need all those programs we use to use on XP and older. Their are some 3rd party programs many of us still use. Just ask before using and we will help.
Microsoft's anti virus is also used by millions of people all over the world.
Microsoft Security Essentials - Microsoft Windows
It's free from Microsoft. I use it on 3 computers and I'm very happy with it.
Another very good free program you will see mentioned many times on this site is
Malwarebytes Anti Malware. Their is a free and a Pro version. I have used both and they are great.
Malwarebytes
Another program many of us use is Ccleaner.
CCleaner - Download
With any program that cleans you must be careful. For a new person I don't recommend use the register cleaning section in Ccleaner. Their are thousands and thousands of registry entries. Make one mistake and you have made a door stop out of your computer.
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You will find that this Forum has the best Tutorials for Windows 7 on the web. They are found at the top of every page. Seldom will you ever have to leave this Forum for a Tutorial. Here is one of them you can read through. You don't have to do everything in the Tutorial but it will give you a good idea of things you can do. I recommend reading through it at least twice. Don't do everything at one time.
http://www.sevenforums.com/tutorials/11728-optimize-windows-7-a.html
We do two major things on this Forum
1. Help others
2. Learn form others
If you ever have a question just post it. Some one is always here.
All programs I have mentioned in this post I use.
Happy computing.