Yes I did, I placed it into the folder that NPGrabba was originally extracted to (and is still in so they are both in the same place).
It's "accounts.txt" and so far the only text in the thing is Username:password just like that.
However, when I load NPGrabba I still just get a white box. Do I need a folder for the accounts.txt somewhere? Nothing appears in the white box that looks like it would be the area for the account stuff to go in.