SQL Server MSDTC service - do you need it or not?
MSDTC - Microsoft Distributed Transaction Coordinator should be installed (Service up and running) when executing the BEGIN DISTRIBUTED TRANSACTION statement that controls the completion of the transaction. So to complete this transaction with a subsequent COMMIT TRANSACTION or ROLLBACK TRANSACTION statement is issued for the session, the controlling instance requests that MS DTC manage the completion of the distributed transaction across all of the instances involved.
By experience I can say unless you are using Distributed Transactions you should enable this service and grant necessary permissions on top of rebuilding on a Clustered instance when it is necessary as per KBA294209 link. Books Online (BOL) refers the underline activities of this as: Normally, all transaction management commands are sent through the SQL Native Client ODBC driver to the server. The application starts a transaction by calling SQLSetConnectAttr with the autocommit mode turned off. The application then performs the updates comprising the transaction and calls SQLEndTran with either the SQL_COMMIT or SQL_ROLLBACK option.
So if you are not using distributed transactions, making use of linked servers remote procedures or SQL not installed on a clustered instance, then no need to worry about MSDTC service on the server. Otherwise you need to set it up properly, also I never had any issues in leaving it as it is even though if you are not using any of the above tasks. Further information the Clustering enviornment refer to SSPClustering articles & KBA260758 in addition to the blog http://blogs.msdn.com/sqlblog/archive/2006/10/06/MSDTC-and-SQL-Server-on-a-cluster.aspx that explains much of the tasks needed.