Most viruses and infections in computers are self inflicted by either clicking on links in emails or being fooled into going to websites that install a malicious code. Some is even unwittingly downloaded along with "free" software. To give yourself protection from a malicious attack, set up a password protected administrator account on your computer.Then ,for any web browsing or any connecting to the internet whatsoever, set up a standard user account. If software tries to install on your computer from that point on, windows will ask for your password for the administrator account. If you do not provide it,the software can not be installed without your consent.
Hint: this is all done in the control panel area named users and groups or users and family or something named to that effect.
Under no circumstance should you log onto the internet under an account with full admin rights,it is an open door to infection!!
PS use almost any browser but internet explorer as it has the most vulnerabilities. Also consider removing java as it is a security risk that will no longer be supported. The chrome browser has its own built in version of a flash player that will be constantly updated with the browser updates,so I would think it is a safer bet than IE.