The Reader software is compatible with Vista (it's not compatible with Macs). Some people have problems loading it. If you want to give it a shot before you buy, you can hop over to
http://ebookstore.sony.com and download it (you don't need the device to download the software).
The 505 page turning is kind of slow, in comparison to newer models out there, but honestly you adjust to it extremely quickly.
You can read PDFs on the 505, but the 700 is better. What it does is it reflows it, and you don't scroll around. It makes the pages longer, so you turn the page to get to the bottom of the text. It doesn't work well with image heavy documents. Do you have a lot of PDFs?
That being said, I friggin love my 505
