You don't have to pay for expensive anti-virus software to protect your computer. There are many free anti-virus software that you can download and it won't cost you a cent.  Even if you have viruses on your computer at the moment, you can find free online virus scans that will find the viruses and remove them automatically.

The free software is usually always up to date and if you do the online scans you won't have to worry about constantly updating your computer for it to find the newest viruses. It will be done automatically.