Can hackers read everything on my computer?

Weeelllll.....

I don't want to disagree with your local computer guru, but I think he or she might be speaking a bit imprecisely based on what you're saying.

It is true that if a hacker has your computer they can probably dig up things you'd prefer to keep private, including a file that contains your passwords (which seems like a dangerous strategy, btw, unless you at least keep that file password protected) but without explicit access and without the aid of a virus that's already running on your computer that they control, it's hard for me to envision exactly how they could see what's in your computer's memory.

On the other hand, it is quite possible - and disturbingly easy, actually! - for even a neophyte hacker to be sniffing login account and password information from a wireless network, whether it's public or private. (A private, password-protected network protects you from people who aren't on the network, but if you're at a cafe, say, where they have the password posted on the cash register, then everyone who is online is "trusted". Dangerous!)

As a scary experiment, go to Google and search for something like "wireless password sniffer" or "wifi packet sniffer" or similar and you'll find that there are applications that are easily downloaded - and free - that will let anyone start monitoring the wireless network traffic around them.

This is the tip of a much bigger topic, of course, and there are a variety of best practices you should learn so you can stay secure on wireless networks, but I'll just start by saying that you should never log in to a Web site that isn't protected by SSL (that is, its URL is "https://" rather than "http://"). More importantly, you can also use a secure SSL connection to communicate with your mail server: call your ISP to get details of how to switch to that.

Hope that clears things up. If you are the "computer guru" who wrote this original note, by the way, please do explain what you were thinking!