[Centos] Centos 4

Has anyone done an upgrade from RHEL3 to RHEL4? Is this likely to break 
a lot of things? How long will Centos be supporting version 3? I just 
installed Centos 3.4 two weeks ago!

The only problem I'm having with Centos is that the perl is a bit old. I 
have errors with spamassassin. So far bugzilla for spamassasin is 
blaming it on the version of perl included in RHEL3 and bugs in the 
'taint' code. I see that RHEL4 has newer Perl packages.