@ K-Mac,
Don't bother trying the "new" F/W.
The F/W versions you reference are the same.
I installed it as per suggestion from dlink tech support and this is the version of my 655 now
Firmware Version : 2.00NA , Wed, 12, May, 2010
(no change)
The Download dated September 16, 2010 is a zip file.
ftp://ftp.dlink.com/Gateway/dir655_revB/Firmware/dir655_revB_FW_200NA.zip
Which contains
1. the May 12, 2010 F/W (file is dated 11 May but when loaded into 655 shows 12 May)
2. dir655_revB_release_notes.txt file
Hope this helps.