Welcome to the internet, if you have a public ip it will be scanned/sweeped at least once an hour. This don't mean they are targeted attakcs against you, and it definitely doen't mean they are successful. How would the situation change with a firewall appliance?

If you make sure you always have the latest updates installed, run an antivirus, turn on the windows firewall and refrain from installing shady stuff and clicking on every exciting link on the interwebs, there's no need for any additional software nor hardware.