[Centos] question about centos4

[michiele at info.nl (Michiel van Es)]

Hi ,
I've got a question about CentOS 4:

-Can I upgrade CentoS 3.* to CentOS4 with yum or do I have to use the 
cd-rom and linux upgradeany option?

-Are there any CentOS 4 mirrors (updates/packages etc?)

I found one on belnet.be but it hadn't had any updates?

Thanks in advance.
-- 

Michiel