One thing I find that helps a lot to keep you safe is firefox. Then go to Tools - Add-ons then download a add on called Adblock Plus it will stop a lot of pop ups the common way to put a virus on your PC.
I recommend Spybot Search & Destroy, besides the fact that it can detect a lot of viruses, trojans etc. it also lets you know if something is trying to modify your computers registry. A trojan called Vundo aka Virtumonde adds itself in the registry and makes itself a part of winlogon.exe so that it runs everytime you start your computer, and it's in such situation that the having Spybot keep an eye on the registry is good.
Hi ThisIsTunakTunak, yes definitely you can! That is why you really need to protect your pc as much as possible. Make sure you have an anti-virus installed, which has the latest virus updates. It is also good to install and anti-spyware / anti-adware software to help you be even more protected.