And we can make the best firewalls in the world, get you to change your password every 20 days, create servers with secure channels for clients to use, etc - but it all runs on hardware built in the countries where the malevolent person is attacking you from.
And new software comes out every day, all ripe for exploitation. And, very likely, new would-be cybercriminals learn new techniques every day.(Note - not talking about hacker who are just trying to see how things work, go in and out. I mean people with truly malevolent leanings.)
On top of that, you have thousands of "companies" who want to hire someone for $23,000 a year to run120 windows servers, from NT to 2012, 3 sql databases, keep their single user Access database running on a network and shared by 250 people, 75 desktops with varying years of operating systems, and, oh yeah, take care of all the security too. And complain that the IT people cost too much.
So, really, what is needed is some kind of magic firewall that will protect us from all of our own bad behaviors while still allowing us to do anything we want. Kinda like that fence the teabaggers want to build around the country. Both are problematic.
All you can really stop is most of it. There are literally hundreds of thousands of potential criminals out there every day, and as long as you expose your network to the world, they have nothing to lose by trying to get in.
It's not an ignorant question at all - you are concerned about your job, your bank account, etc, and you have every right to be. But the worst problem is the people who lead you to believe there is a solution, and there isn't, unless one thinks that telling people not to be bad is going to work. . It's on ongoing, evolving process, with winners appearing on both sides from time to time.
Just do the best you can, and have a backup plan where possible.
= new reply since forum marked as read