OFED Q and Deciphering the contents of /etc/dat/conf

Hello I have installed Intel MPI both V4.0.0 and V3.2.2 on an Nehalem QDR IB Cluster (fabric is Voltaire GridDirector 4700).

We are using RHEL and CentOS 5.4 with OFED 1.4.2. Is there any issue with staying with 1.4.2 or should we move to OFED 1.5.0? Or shou;d we wait unti 1.5.1 is out?

Another question I have relates to how IMPI interfacs wirth the underlying OFED stack. I couldn't find info on the ref manual. How is the contents of /etc/dat.conf interpreted ?

thanks and sorry for the many Qs.

Michael