After spending hours trying to figure out how to authorize my Sony PCS-700, I finally found an answer on the mobileread website. I had installed the Sony eReader and Adobe Digital Editions. I was able to download and load books using the eReader but Adobe Digital Editions did not recognize my reader. Nothing on the Sony site or on the Adobe Digital Editions site resolved the problem. However "igorsk" on www.mobileread.com had a post on the manual installation of the eBook Library (http://www.mobileread.com/forums/showthread.php?t=26849&highlight=pim). I only needed to use the direction related to PIM found in that post and it worked!
I think the problem is related to where you locate the Sony eReader and the Adobe Digital Editions. I believe they have to be on the same drive and I think that drive needs to be the C: drive. I had both of those programs located together on a different drive. I sure hope this post saves someone the hours of aggravation that I endured and many, many thanks to "igorsk".