Computer security issues are a problem for computer users especially those connected to the internet. Doing nothing is not the safest option anymore without you never go online. There are some responsibilities that need to be taken to make sure your computer is secure.
First, get the latest and updated virus and spyware scanners. These do not completely protect a computer, but it's one of the best options for protection. Run these regularly especially in safe mode to get rid of viruses that are harder to remove.
Be careful about which domains you go to when clicking on links in email. Many sites might look like PayPal and ask for your user name and password but in reality it's not PayPal. Never click links in emails and insert personal information. Go to the site first from your browser window instead of trying to click provided links as this is safer.
Do not download software or applications from untrusted sources. Many people get all sorts of issues by downloading files especially illegally. If you are not sure about it, do not open up the file or email attachment.
Keep your Windows operating system and the software you use updated. This also includes the plugins in your browser like Flash support. Many times there are vulnerabilities that are patched with the updates. Not having these updates leaves one open to attacks.
Although it may seem burdensome consider reinstalling the operating system from time to time. There are many lingering issues that can be on a computer that are hard to remove. A complete reinstall will get rid of all the problems like viruses or even worse botnets.
If you continue to have problems, using Mac OSX or Linux like an Ubuntu computer might be best for surfing the internet. These operating systems do not have as many of these issues and security problems.