[CentOS] NFS and iptables issues

I've got a newly installed Centos 5.0 box, planned to replace an ageing server
(solaris box).  I've set up the nfs shares, but the other solaris boxes
won't mount them, unless I turn of iptables on the Centos box.  If I do that,
they mount, and all operations tested to date work fine. 

Iptables is allowing the 2049 tcp and udp ports already.  What else needs to
be opened up in iptables for nfs to work through the firewall?

I looked at the RHEL system admin guide on NFS and found nothing useful.

thanks,
-chuck