The alert is too different kinds for the most part- One sees if there is an open portal (port on the machine that can be used to access it thru the internet) There are quite a few even though only some are used to enter. The other is a direct attempt to get in and that shows when the alert says "blocked access through port so n so from ip address. This is a simple explaination. SHIELDSUP goes a little further and so does the GRC.com site. With a cable modem you are more vunerable due to a constant IP address. Most dialup's that use analog modems have a changing address so the chance of intrusion is only at the time you are on line. Meaning your IP address changes every time you log on usually. Hope this helps a little.

Zone Alarm is the easiest software firewallto use and a must for anyone with Cable?DSL or constant access to the internet. Remember, with these, anytime your computer is on, you are connected and therefore open to attack/probing.