by Fernando de la Cuadra - International Technical Editor, Panda Software
Files can enter your computer for many reasons. Not only can you choose to download a file (through a link in a web page or an FTP session), but you can also receive files from other people through a chat session. Moreover, there are vulnerabilities in some programs that prevent users from being informed of file downloads.
To sum up, keep a close control of things that enter your PC. Increasing the security of your browser takes only seconds and will save you a lot of trouble. Installing a personal firewall is very complex, expensive and only for expert users. If you want to avoid dangerous files from entering your PC, install an antivirus on your computer, let it update itself once a day and relax.