[CentOS] question about updates with centos 3.x / Upgrade to 3.5 for the updates or reinstall all servers with centos 3 ?

Hello

    i have a doubt, if i installed 3.3 , 3.4 or 3.5, i see the mirrors 
removed the 3.1-3.4 i have a 3.3 running ....but i thinked the rhel 
flavors are supposed to long life (3~5 years) but not understand, i to 
upgrade to 3.5 for have the lastest updates?

Reinstall servers to centos 3.5 are big job... or then i have to install 
centos 3 with no revision for have long life s.o for get the updates?

Thanks a lot.

-- 
Cesar Lagarrigue V.
Ingeniero de sistemas
BEE Consultorías y Sistemas

Fono : (562) 231-7131
Fax:    (562) 231-7136

Carmencita 25 Of.62
Las Condes
Santiago de Chile

www.bee.cl