It's not as simple as "yum install" as you can see below and it doesn't stop there.
yum install php53
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* rpmforge: mirror.us.leaseweb.net
* extras: centos.mirror.rafal.ca
* updates: centos.mirror.nexicom.net
* base: centos.mirror.nexicom.net
* addons: centos.mirror.nexicom.net
Setting up Install Process........
[2013/02/22 19:06:37.373564, 0] param/loadparm.c:8004(lp_do_parameter)
Global parameter guest account found in service section!
This is annoying but the solution is simple:
The line "guest account = " is in the section for a share (in /etc/samba/smb.conf), but it should be under globals. Move it under [global] and then everything should be fine.........