[CentOS] unable to write files bigger than 4GB over NFS

This may not be a CentOS problem, because I'm in a mixed environment.  
But I put it out in case anybody has any thoughts.

I recently replaced a file server, which was on a Pentium III based  
system running 32-bit CentOS 4.3, with an Opteron based system  
running Fedora 4. The NFS clients are all CentOS 4.3, some are 32 bit  
and some are 64 bit.

Since the replacement, when I try to write a big file from the 32bit  
CentOS  boxes over NFS to the server, I get "filesize exceed  
messages" at 2GB. However this used to work with the old server. And  
I can  write big files if I'm logged on to the server.

One more oddity, the  shared file system on the server is xfs  
formatted; if I instead mount a reiserfs file system I can  
successfully write. This part does not make sense to me.

And one more, I can write large files from a 32-bit Fedora 4 system  
to the server over NFS, just not from 32-bit CentOS.

I'm exporting with (rw,async) and mounting with  
(bg,rsize=8192,wsize=8192)

Is there some interaction between nfs and xfs that I need to know about?

Thanks,
Tony Schreiner
Boston College