Just bought the PRS-600 and had the same problems +.
Go to
http://www.mobileread.mobi/forums/sh...ad.php?t=40987
I had installed the Sony eBook Library on Win XP before upgrading to Win 7 (64bit). It worked "as software".
I then upgraded Windows and bought the PRS-600.
I could not get it to work/recocnize the ereader.
I also could not uninstall "eBook Library" the normal way and had to download "Revo Uninstaller" to get rid of it.
Then follow the instructions at
http://www.mobileread.mobi/forums/sh...ad.php?t=40987
It now works perfectly with Windows 7 (64bit).