From what little I know about networking, opening ports lets external data get sent in. But how that data is handled is entirely up to the applications running on my machine. So if I'm not running any malicious applications, there should be nothing wrong with disabling the firewall, right? Also, how do applications work when ports aren't forwarded? For example, I need to forward port TCP 6112 to host Blizzard games, but I've heard that HTTP uses port 80, but I haven't forwarded that port, yet Firefox still works. Btw I'm using Windows Vista.