[CentOS] network problems

We just moved a user, who deals with a *lot* of data, to a new server,
since his old NFS home directory was on a disk that had started showing
problems.

Now, i/o is about six times slower, my manager reports.

After a fair bit of googling, I started looking at tc and ip, and found
the following: from ip address show, first, on the old home directory
server,
 eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast qlen 1000
then, on the new:
 eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000

I've tried tc qdisc add dev eth0 mq pfifo_fast
and
tc qdisc add dev eth0  pfifo_fast

and neither works. I've googled, and seen something about you can't set
something with tc, because pfifo_fast is the hardwired default.

Anyone know how I can reset this, or is there a package I can reinstall
that would do that?

         mark