Spyware Warrior

[WhySoCurious]

I recently had someone from my ISP help me out with a password related thing, and soon got to thinking about the safety of it.

What is to keep a person at my ISP from writing down my internet username and password (and yes, they can see it) and then later logging in to my internet account and/or intercepting the passwords or credit card numbers I send out over the internet?

I also got to wondering about how safe their computers are that they use. Their computers can pull up all my account information as well as other customers. If there was a worm or some other kind of malware on their computers us customers would really be screwed. We do our best to keep our computers clean, but to think the problem could be on their end and maybe they don't even know it. So what keeps a nightmare like that from happening?

As for the DSL question, it kind of relates to the first question. They can see the password I use to get my DSL online. But then I also think about how my modem was able to auto detect my internet settings so I just had to enter my login credentials. So will my DSL account only work in my house or other people's houses too?