> 
> 
> When a new update set is released (ie 4.1, 3.5, etc.), only the latest
> [base] and [updates] are included in the main tree.
> 
> Taken together, the base and updates will be the latest version.
> 
> If you install from old media (3.3, 4.0) then you need to have [base]
> and [updates] in your yum configuration.
> 
> (or get the 4.1 ISOs to use as your [base])
> 
So I can yust say
IT IS WRONG
there were a lot of talks about it here:
When you install CentOS x.0 and you run "yum update" you get finaly 
lates CentOS X.Y ...
CentOS X.4 is CentOS X.0 + all released updates ...
and from your answer it seems it is gone
CentOS 4.1 have diferent versions of SW then CentOS 4.0 + updates
I know CentOS depend on RH releases but presented strategy is brain dead
I have several servers with fixed setup and I have local mirror.
Now it seems I have to mirror not only "updates" but "updates" and "base".
Before half a year there was talk about high bandwith, so lets download 
all the stuff.
    Petr Klíma
    e-mail:  petr.klima at madeta-group.cz   MADETA Group a.s.
    phone:   +420 389 136 209             Rudolfovská 246/83
    web:     http://www.madeta-group.cz   370 50 České Budějovice
                                          Czech Republic