re: going wireless
Whoever's network you are using does not have the proper precautions installed, or you wouldn't have gotten in.
As others have pointed out, if you can sneak in, so can someone a lot nastier, and he might punch through to your systems.
My AirPort not only has encryption enabled, but I have set it so that only a specific list of passworded users can use it. I'm not sophisticated about these things, and surely some expert could probably bust in, but it keeps the casual tapper out of there.