hosting software

Hi,

I'm looking to setup a hosting server. I've loked around and there's
packages with RH only and RH with ENSIM or other hosting managment software.
Since cost is factor and plain RedHat packages are cheaper i'de like to know
opinions/experience about this:
.Is Ensim really worth? and wicth one Basic vs Pro
.Are there GPL packages for automating hosting (billing, transfer control)
and do the same as ENSIM? (I found web://cp )

Best Regards,
Jose' Neto