ebooks | Sony software & store (Reply)

I just got a Sony PRS-300, and for the few hours I've had it I'm digging it. I haven't yet bothered to install the software that came with it, since I already had Calibre installed and don't plan on buying from the Sony store. Are there any benefits to using/installing the software in this case? Does it lock-in the device in any way? (I switch between a PC and a Macbook, and don't want any issues.) Do I need to register the device using the software? Are there any freebies in the Sony store that would be different from Fictionwise or Booksonboard? That sort of thing. Would appreciate any opinions!