This has been addressed some time ago, but I've not had any luck following the steps outlined or advice suggested. Here's my situation:
I've installed SQL Server '05 and have another (non-Ruby) application utilizing it successfully.
I've got Rails up and running successfully (but only for MySQL.)
I've installed the Rails sqlserver adapter gem (as well as its dependencies.)
I've downloaded ADO.rb (now only available on older builds of Ruby-DBI) and placed it into c:\ruby\lib\ruby\site_ruby\1.8\DBD\ADO\ADO.rb.
I've configured database.yml to use the sqlserver adapter and pointed it towards my database with valid login information.
When I attempt to run a migration, I get the ugly 'Unable to load driver ADO (uninitialized constant DBI::DBD::ADO)' error.
Thanks immensely for any assistance.