Does your surge protector need replaced? Surge protectors can absorb one big hit or several small ones. If yours has protected your equipment for 2 years or more or has shielded your equipment from a big electrical hit, it may just be an extension cord now. A 500 Joule rated surge protector can absorb one 500 Joule hit or ten 50 Joule hits. Even 500 one Joule hits will make your surge protector worthless when the large hit comes.
ComputerCorps has many new in the box surge suppressors (see above) rated at 790 joules on sale for $10 while supplies last.
Some information comes from a blog post at bad*** extension cords.