[chaley]

I was confused. When I read your posts, I thought you were saying that you had two ereading devices, a 505 and a something. A closer read tells me that you have one device, a 505, an installation of Sony Reader on PC1 and PC2, and an installation of ADE on PC1.

Assuming that you have authorized your 505 with ADE on PC1 and can read books on the 505 that you obtain using that ADE installation, then as dwanthny said, you can copy those books between computers using any method that works for you. You can move them to/from the 505 using Sony Reader (or Calibre or what-have-you) installed on any computer. You will be able to read the book on the 505 no matter what path it uses to gets there.