Not to change the discussion, but quick question, why do so many people mod their consoles? To me it seems pointless and ruins the console. :s
Well there two types of modding.
Hard-mods: This would be soldering a modchip to the ps2 to play backups games. For the most part its simpler than soft-modding. It ruins the "virginity" of the ps2 for collectors they most likely want one that isn't opened.
Soft-mod: Uses a software exploit to do the same thing a hard mod does. Usually doesn't require opening up the system. Can be removed from the system so manufacturer would never be able to tell that you modded it. Usually requires certain games or peripherals that can cost a lot of money or you might have to open the ps2 to block sensors. If you know someone with a modded card then you can just ask them to install the exploit for you. The hard part is usually running unsigned code.
Both method enable you to play games off the hard drive/usb drive/firewire/ or stream over a network thus saving your laser from its inevitable death.