I do computer support for a living so I am somewhat of an expert on general computer issues, but NOT Newsbin.
This kind of question comes up often with my clients. What I tell every one of them is to:
1. get a good anti-virus program. Keep it up to date with updates. Run a full scan once a week or more often.
2. get a good anti-malware program. Keep it up to date with updates. Run a full scan twice a week or more often.
3. get a good backup imaging program. Create an image once every couple of months or so. More often if you are making a lot of changes to your machine. Much more often if you have critical data on the machine.
4. practice safe computing. Don't visit sites that offer porn and/or warez since most are loaded with viruses. Don't download warez unless you know how to do it safely since most warez are loaded with viruses. The porn and virus warnings have nothing to do with my moral standards, they are only because of the danger of viruses, scams, identity theft, etc.
5. never, ever, take anything that is free unless you are enough of an expert to know it is safe and it will not slow down your machine. Many, many free things are bad for your machine. Examples are browser add on's, coupon gathering programs, instant weather access buttons, etc. Not all of these are bad, but many are.
6. (WARNING...start of sarcasm) please ask your friends and relatives to make "improvements" to your computer (END of sarcasm). I love them helping you because it generates more income for me in fixing the mess they make.
Find a good computer support professional who can help you with problems and questions. My clients don't need that advice because they have me, LOL. The kid next door is nice to have because he is cheap and convenient, but a good professional has a different point of view. They should, for example, be more concerned with you not loosing data than with the speed or color of your machine