If you want to run dasBlog on Windows 2003 64bit IIS6, download the 32bit version and make the following changes.
You will need to replace the 32bit "BasicFrame.WebControls.BasicDatePicker.dll" with the 64bit version available in the source directory "lib".
The file is "BasicFrame.WebControls.BasicDatePicker.dll.64bit", rename it and replace the file"BasicFrame.WebControls.BasicDatePicker.dll" in your "bin" directory.
Restart IIS and problem solved.
I understand that the compiled version of dasBlog 2.0 is supposed to be CPU agnostic, except for the date picker, which was provided to Microsoft as a freebee created bit specific (a 32bit version and a 64bit version is included in the source, the default setup is for the 32bit .dll).
I understand that dasBlog on Vista IIS7 is a little more involved you may want to read Scott Hanselmans blog on the subject.