I have the exact same router specs and 1.14 works fine for me (1.15 may also work for you). I believe you'll need FW 1.30 or above to use Shareport 3.0.
Get 1.14 here: ftp://ftp.dlink.com/Gateway/dir625_revC/Apps/SharePort_Network_USB_Utility_114.zip and
1.15 here: ftp://ftp.dlink.se/Shareport/SharePort_v1.15.9_setup.zip.
If you have problems making it work, check out http://forums.dlink.com/index.php?topic=12193.0 and other postings.
/Kresten