My brother works at an ISP and told me this story...
An old lady calls in with a slow speed issue. My brother had the lady go to some speed test sites, checked the modem's freqs, checked for ICMP flooding, T3 and T4 time outs, the works. My brother is like, this has got to be an issue with her PC. So he asks her if she made any changes to your computer in the past week or so? The old lady goes, the boy across the street installed a firewall for me. My brother was like, that's got to be it! He goes ahead and asks her the firewall name. She replies, it's a linksys... however the boy next door said it won't work unless i put it next to the window. Come to find out all the neighbor kids were enjoying highspeed internet, compliments of her "firewall".