I'm using this CentOS version:

# lsb_release -a
LSB Version: :core-4.0-amd64:core-4.0-ia32:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-ia32:graphics-4.0-noarchrinting-4.0-amd64rinting-4.0-ia32rinting-4.0-noarch
Distributor ID: CentOS
Description: CentOS release 5.6 (Final)
Release: 5.6
Codename: Final
I'm using zcs-7.1.0_GA_3140.RHEL5_64

I noticed that there are several system upgrades that can be installed, I can do that safely via yum?
Should I first install Zimbra upgrade (through admin web interface)?
Thank you!