Google has updated it's look, but you can still use the old interface (as of 5/25/10). Look at the top-right of the screen and click "previous interface".
I might be wrong, but I don't think you need to have an Adwords account to use the tool. I do have an Adwords account but I did not have to login to use the keyword tool and the screen does not show me as being logged in when I use it.
Your problem with the site disappearing might be because of something else. If it's still happening, try downloading the data before the 2 minutes runs out.