i386 vs. x86_64

I’m getting ready to roll out a medium size installation of Nagios (Monitoring 50-odd Solaris and Linux machines, < 1,000 checks). Our proof of concept was implemented on 32 bit (i386) CentOS. Our production environment will be on a virtual machine on a VMware server.

The thought occurred to me that perhaps I’d be better of starting with a 64 bit system. Are there any stability or performance advantages of choosing the x86_64 version of CentOS instead of i386?