That depends om what you mean by safe, some level of safety can be reached even in a standard computer that you use everyday, but your coins are never going to be completely safe, if you can live with that level of security then installing your favourite Linux distribution in your PC that you have verified is clean from any alteration and navigate the internet with good habits can be enough to keep your coins secure.

However if you have an amount of money in cryptocurrencies that you consider to be important then you must invest in a hardware wallet, it is unforgivable that some people have claimed to have lost hundreds of thousands of dollars and they were storing their coins in a Windows machine.