Kang--Glad you found this place! Hopefully it'll help you enjoy your reader much more.
I know that it's been a tremendous help for me! I've learned so much from here about converting books, etc--and have read several of the books that a lot of people have taken incredible amounts of time to convert to the Sony Format.
Like Elsi says--avoid PDF if at all possible. Now with the new firmware, I have downloaded a few Adobe Digital Edition books from my library and have read them on my 505. Since these are free, I'm not complaining because they are readable, but I wouldn't want to pay for them. Books formatted in the Sony LRF format work much better on the reader.
dordale