rails and mssql

We are developing a solution for a client. Today he is using ASP.NET
with SQL Server 2008 and wanna use SQL Server 2008 as database for the
Rails application as well.

So, they were asking us why Active Record uses unixODBC to communicate
with SQL Server instead of using only freeTDS - they were concerned
about performance problems.

We googled the subject a little bit, and we weren't able to find any
Ruby solution that uses solely freeTDS. They all used unixODBC in some
sort of way.

Questions:

1) Why the freeTDS solutions out there always uses unixODBC in some
sort of way?
2) Is it possible to communicate with SQL Server using only freeTDS?
3) Will we gain any performance using only freeTDS instead of freeTDS
+ unixODBC

Thanks in advance.

I used SQL Server 2005 for 18 months for a rails application. I recall
having to use both freetds and unixodbc to get the connection to work.
I'm a little hazy on this, but I think one is a higher level
communication protocol, and one is a lower level communication
protocol. Google the rest if it helps