ShieldsUp - check your firewall

Are you really in any danger?

The Internet is full of great information and many useful resources. But it also contains things that crawl around in the dark and go bump in the night. I think you'll be as surprised as I was to learn how much of that is really happening today.

Yes, there can be no question that you're in danger:
If your computers are only connected to the Internet briefly, when you're browsing the web or retrieving and sending eMail, your connection exposure will be minimal. But if you are one of the millions of people who are discovering the amazing power and convenience of a persistent connection to the Net — through a cable modem or DSL line — and if you leave any of your computers on and connected for hours at a time, then your exposure is substantially greater.
" But the Internet is a BIG place. What's the chance, really,that my little computer would even get noticed? "
That's a very good and reasonable question, but the answer might frighten you as it frightened me. Here's the crux of it:

There are MANY FREELY AVAILABLE "scanners" being run by badpeople who are sweeping the Internet looking SPECIFICALLY forcomputers running Windows File and Printer Sharing! And if thoseshares are password protected and sufficiently interesting, anyfreely available password cracker will silently pound on yourpassword until your defenses have been penetrated!

https://www.grc.com/x/ne.dll?bh0bkyd2